Synthetic nanostructures including nucleic acids and/or other entities

ABSTRACT

Articles, compositions, kits, and methods relating to nanostructures, including synthetic nanostructures, are provided. Certain embodiments described herein include structures having a core-shell type arrangement; for instance, a nanostructure core may be surrounded by a shell including a material, such as a lipid bilayer, and may include other components such as oligonucleotides. In some embodiments, the structures, when introduced into a subject, can be used to deliver nucleic acids and/or can regulate gene expression. Accordingly, the structures described herein may be used to diagnose, prevent, treat or manage certain diseases or bodily conditions. In some cases, the structures are both a therapeutic agent and a diagnostic agent.

FIELD OF INVENTION

The present invention generally relates to synthetic nanostructuresincluding nucleic acids and/or other entities. The nanostructures may beused for therapeutic and/or diagnostic applications.

BACKGROUND

Nonviral nanoparticle (NP) formulations are being developed to addresshurdles inherent to the targeted cellular delivery of short therapeuticnucleic acid (NA) oligonucleotides (e.g. antisense-DNA (AS-DNA), siRNA,and microRNA). Chemical approaches are being employed to endow varioussynthetic NP platforms with ever-increasing biomimetic capacity toenhance the NPs' ability to overcome interfacial hurdles that arise whencellular biological systems are exposed to synthetic nanostructures.Although there has been progress in the area of nucleic acid deliveryand gene regulation, improvements would find application in a number ofdifferent fields.

SUMMARY OF THE INVENTION

The present invention generally relates to nanostructures includingnucleic acids and/or other entities. The nanostructures may be used fortherapeutic and/or diagnostic applications. The nanostructures may findutility for the targeted in vivo delivery of nucleic acid therapeuticsfor any number of disease processes, including, but not limited to,atherosclerosis, inflammation, and cancer. The subject matter of thepresent invention involves, in some cases, interrelated products,alternative solutions to a particular problem, and/or a plurality ofdifferent uses of one or more systems and/or articles.

Several methods are disclosed herein of administering a subject with acompound for prevention or treatment of a particular condition. It is tobe understood that in each such aspect of the invention, the inventionspecifically includes, also, the compound for use in the treatment orprevention of that particular condition, as well as use of the compoundfor the manufacture of a medicament for the treatment or prevention ofthat particular condition.

In another aspect, the present invention is directed to a method ofmaking one or more of the embodiments described herein, for example,structures including nanoparticle-templated biomimetics. In anotheraspect, the present invention is directed to a method of using one ormore of the embodiments described herein. The structures, in someembodiments, may include a nanoparticle-templated biomimetic of highdensity lipoprotein (“HDL NP”). For example, the structure may have thesame or similar shape, size, and/or density as an HDL, and/or thestructure may include surface features and/or surface concentrationsthat resemble endogenous HDLs, for example the presence of Apo A-1(apolipoprotein) and/or Apo A-II, and/or their components. Thestructure, in some embodiments, may include phospholipids that resemblethose found in endogenous HDLs. In some embodiments, the structure mayinclude a nanostructure core formed of gold; it should be understood,however, that other nanostructure cores and materials can be used astemplates to form biomimetic structures in other embodiments.

One aspect of the invention is generally directed to the fabrication,directed tailoring, and in vitro characterization of biomimeticnanostructures which naturally interface with biological systems todeliver nucleic acids. High density lipoproteins (HDL) are naturallycirculating human nanostructures with a multitude of beneficialfunctions. HDLs naturally target specific cell types includingendothelial cells, macrophages, and hepatocytes. Using a bottom-upsynthetic approach, structures with similar size, shape, and/or surfacechemistry to natural mature spherical HDLs may be prepared, as discussedherein, to form structures such as HDL NPs. In some embodiments, the HDLNPs function comparably to their natural counterparts in biologicalsystems to efflux and transport cholesterol. Accordingly, in one set ofembodiments, structures such as HDL NPs may be used to assess howbiomimicry may be used to successfully integrate functional hybridnucleic acid-HDL NPs (NA-HDL NPs) into biological systems for nucleicacid delivery.

One aspect of the invention is generally directed to sphericalNP-templated HDL biomimetic structures. The binding constant of thesestructures to cholesterol may be, for example, less than theconcentration of total cholesterol in vivo. In some embodiments, thebinding constant of these structures to cholesterol may be less thanabout K_(d)=10 mM. These structures may be engineered to mimicendogenous spherical HDLs. For example, in some embodiments, thestructures have a binding constant to cholesterol (or another lipid suchas a triglyeride) that is substantially similar to that of endogenousHDL. The surface components of the HDL NP structures, in one set ofembodiments, includes those of natural HDL. For example, 2-3 copies ofApo A-1 may be embedded within a layer of NP-adsorbed phospholipids, inone embodiment. The HDL NP structures may have any suitable size, e.g.,as described herein. In some embodiments, the HDL NPs can enhancereverse cholesterol transport from cells, such as both murine (J774) andhuman (THP-1) macrophages grown in culture. Furthermore, a portion ofthe HDL NPs may be taken up by the cells where they have significantcytoplasmic localization. The structures also include one or moredifferent nucleic acids in some embodiments.

In some embodiments, the structures are modified to include more thanone functionality. For example, the structures may besurface-functionalized with thiol end-modified oligonucleotides (i.e.DNA, RNA, siRNA, mRNA, etc.). Structures may also be surfacefunctionalized with thiol-modified oligos able to regulate geneexpression. These structures may have increased affinity forcomplementary nucleic acids compared to unmodified oligonucleotides,reduced susceptibility to nuclease degradation, have greater than 80%,85%, 90%, 95%, 97%, or 99% cellular uptake, and/or exhibit little or notoxicity. The surface density of bound oligonucleotides to thestructures may also be controlled, e.g., to show gene knockdown.Oligonucleotides such as DNA, RNA, or siRNA may be attached to ananostructure core using techniques such as electrostatic adsorption orchemisorption techniques, for example, Au—SH conjugation chemistry.

One set of embodiments is generally directed to certain nanomaterialstructures capable of addressing macrophages and hepatocytes for uniqueand highly potent dual activity. Thus, the structures may function inboth cell types. Design of such structures may involve, for example,balancing the surface coverage of siRNA so as to not, potentially,decrease the capacity for the structure to mediate reverse cholesterolefflux and vice versa.

In one set of embodiments, a series of structures are provided. In oneembodiment, a structure comprises a nanostructure core, a shellcomprising a lipid surrounding and attached to the nanostructure core,and an oligonucleotide adapted to regulate gene expression associatedwith at least a portion of the shell. The structure may be adapted tosequester cholesterol.

In another embodiment, a structure comprises a nanostructure core, ahydrophobic shell surrounding the nanostructure core, and anoligonucleotide adapted to regulate gene expression associated with atleast a portion of the shell. The structure may be adapted to sequestercholesterol.

In another embodiment, a structure comprises a nanostructure core, and acholesterol-modified oligonucleotide associated with the nanostructurecore.

In another embodiment, a nanostructure comprising an oligonucleotideadapted to regulate gene expression, a lipid, and an apolipoprotein.

In another embodiment, a nanostructure comprises an oligonucleotideadapted to regulate gene expression and apolipoprotein A1.

In some instances, a method includes delivering a structure describedherein to a subject or a biological sample, and regulating geneexpression in the subject or biological sample.

In some embodiments, a pharmaceutical composition is provided. Thecomposition may include a structure described herein and one or morepharmaceutically acceptable carriers, additives, and/or diluents.

In some embodiments, a kit for diagnosing, preventing, treating ormanaging a disease or bodily condition is provided. The kit may includea composition comprising a plurality of structures described herein, andinstructions for use of the composition for diagnosing, preventing,treating or managing a disease or bodily condition.

In certain embodiments, the structures described herein are singleentities that can be used as both a therapeutic and a diagnostic agent.

In another set of embodiments, a series of methods are provided. In oneembodiment, a method for diagnosing, preventing, treating or managing adisease or bodily condition. The methods involves administering to asubject a therapeutically-effective amount of a composition comprising astructure described herein, e.g., a structure comprising a nanostructurecore comprising an inorganic material and a shell surrounding andattached to the nanostructure core. The structure may be adapted tosequester cholesterol (or other lipids or molecules in certainembodiments). The method may include allowing the structure to sequestercholesterol, e.g., at least 2, at least 3, at least 5, 20, or 50molecules of cholesterol. The cholesterol may be, for example,esterified cholesterol or free cholesterol. In other embodiments, amethod involves allowing the structure to sequester molecules of aparticular type or composition, e.g., at least 5, 20, or 50 molecules ofa particular type or composition. The structure may be adapted toregulate gene expression in sample or a patient.

Other advantages and novel features of the present invention will becomeapparent from the following detailed description of various non-limitingembodiments of the invention when considered in conjunction with theaccompanying figures. In cases where the present specification and adocument incorporated by reference include conflicting and/orinconsistent disclosure, the present specification shall control. If twoor more documents incorporated by reference include conflicting and/orinconsistent disclosure with respect to each other, then the documenthaving the later effective date shall control.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting embodiments of the present invention will be described byway of example with reference to the figures, which are schematic andare not intended to be drawn to scale. In the figures, each identical ornearly identical component illustrated is typically represented by asingle numeral. For purposes of clarity, not every component is labeledin every figure, nor is every component of each embodiment of theinvention shown where illustration is not necessary to allow those ofordinary skill in the art to understand the invention.

FIG. 1 shows an example of a structure that can be used to delivernucleic acids and/or other entities according to one set of embodiments;

FIGS. 2A and 2B show methods for fabricating various structures that canbe used to deliver nucleic acids and/or other entities according toembodiments described herein;

FIG. 3 shows a method for fabricating structures including one or moreapolipoproteins and one or more oligonucleotides according to one set ofembodiments;

FIG. 4 shows a method for fabricating structures including differentcomponents that form a shell of the structure according to one set ofembodiments;

FIG. 5 shows results of toxicity experiments of structures delivered tohuman umbilical vein endothelial cells (HUVECs) according to one set ofembodiments;

FIG. 6 shows micro RNA-210 regulation by structures in HUVECs induced toexpress miR-210 using CoCl₂ hypoxia induction according to one set ofembodiments;

FIGS. 7A-7C are electron micrographs showing murine J774 cellstransected with structures described herein according to one set ofembodiments;

FIG. 8A shows relative expression of miR-210 levels in HUVECs accordingto one set of embodiments;

FIG. 8B shows LDH toxicity toward HUVECs according to one set ofembodiments;

FIG. 8C shows miR-210 knock down in HUVECs using structures describedherein according to one set of embodiments;

FIGS. 9A-9D are fluorescent confocal microscopy images showing cellulardistribution of structures described herein in PC3 cells according toone set of embodiments;

FIGS. 9E-9H are transmission electron microscopy (TEM) images showingcellular distribution of structures described herein in PC3 cells;

FIG. 10 shows toxicity data for various structures described hereinaccording to one set of embodiments;

FIG. 11 shows the results of chemically inducing hypoxia in PC3 cells byexposing them to cobalt chloride according to one set of embodiments;

FIG. 12 shows relative miR-210 expression in PC3 cells after treatmentwith various structures described herein in serum-containing andserum-free media according to one set of embodiments;

FIG. 13A shows relative miR-210 expression in PC3 cells after treatmentwith various structures described herein according to one set ofembodiments;

FIG. 13B shows a western blot assessment of E2F3a, a target of miR-210,showing that treatment of PC3 cells with certain structures describedherein de-represses E2F3a according to one set of embodiments;

FIG. 14 shows a time course of miR-210 knockdown in PC3 cells treatedwith various structures described herein according to one set ofembodiments;

FIG. 15 shows examples of components that can be used to allow releaseof nucleic acids from structures described herein according to one setof embodiments;

FIGS. 16A and 16B are transmission electron microscope images ofmixed-monolayer functionalized nanoparticles according to one set ofembodiments; and

FIG. 17 shows LnCaP prostate cancer cells transected with mixedmonolayer functionalized nanoparticles according to one set ofembodiments.

DETAILED DESCRIPTION

Articles, compositions, kits, and methods relating to nanostructures,including synthetic nanostructures, are provided. Certain embodimentsdescribed herein include structures having a core-shell typearrangement; for instance, a nanostructure core may be surrounded by ashell including a material, such as a lipid bilayer, and may includeother components such as oligonucleotides. In some embodiments, thestructures, when introduced into a subject, can be used to delivernucleic acids and/or can regulate gene expression. Accordingly, thestructures described herein may be used to diagnose, prevent, treat ormanage certain diseases or bodily conditions. In some cases, thestructures are both a therapeutic agent and a diagnostic agent.

Seamless integration of nano-biomaterials into biological systems isimportant for non-viral delivery of nucleic acids. Fabrication of suchmaterials is important in order to fully realize the potential ofnucleic acid-based therapies. One aspect of the invention combines abiomimetic nanostructure platform with rational nucleic acid chemistryto synthesize gene-regulating biomaterials. In some embodiments, hybridnucleic acid-biomimetic structures can be fabricated to successfullynavigate the bio-nano interface for targeted and chemically triggeredrelease of regulatory nucleic acids. Anchoring the platform, in one setof embodiments, is a synthetic nanoparticle-templated structure, such asa nanoparticle-templated biomimetic of high density lipoprotein (“HDLNP”).

Lipoproteins circulate in the human body and transport hydrophobicmolecules (e.g., cholesterol). HDLs have myriad of beneficialphysiologic functions including, most notably, the prevention ofatherosclerotic cardiovascular disease. Functionally, HDLs naturallytarget specific cell types (e.g., endothelial cells, macrophages,hepatocytes), are internalized by them, may transfer cholesterol, andare then re-introduced into the circulation. In some embodiments, byusing a nanoparticle scaffold as a nanostructure core, the surfaceprotein and lipid components of naturally occurring mature spherical HDLcan be assembled. From the standpoint of size, shape, and surfacechemistry, the resultant HDL structure may be a mimic of natural HDL. Atthe core may be a nanoparticle, such as an inorganic nanoparticle (e.g.,an AuNP) with potential for biomolecule attachment, such as nucleicacids (e.g., oligonucleotides). The inorganic nanoparticle can beoptionally removed to produce a hollow or partially-hollow core in someembodiments.

Although much of the description herein refers to gold nanoparticles(e.g., as use as templates or nanostructure cores), it should beunderstood that this is by way of example only, and that otherstructures and materials can be used as templates or nanostructurecores.

In one set of embodiments, synthetic methods for attaching nucleic acidsto the surface of nanoparticles (e.g., HDL NPs) are described. Solidphase nucleic acid synthesis may be employed to produce a suite of DNAor RNA oligonucleotides end-modified with functional groups, such ascholesterol and alkyl-thiols, for attachment to nanostructure cores.Systematic tailoring of a nanostructure core with oligonucleotides canbe used to obtain control over surface chemical composition. It isbelieved that the surface chemistry at least partially controls certainbio-nano interfacial interactions.

In another set of embodiments, solid-phase DNA chemistry is used totailor synthetic oligonucleotides for DNA-nanoparticle (e.g., HDL NP)attachment. For instance, nucleic acid release from the resultingstructure may be useful in certain applications. In yet another set ofembodiments, the present invention is directed to the gene regulatingcapacity of the nucleic acid-modified nanostructures in cell culture. Inrelatively high throughput, the function of such structures can beassessed in a model system to show structure-function relationships.Importantly, the functional impact that deviation from biomimicryimparts may be inferred by surface chemistry (e.g., nucleic acid releasemechanism), and can be directly tested to derive a mechanism for optimalbio-integration of a hybrid DNA-HDL NPs.

Specifically, in some embodiments, the present invention is directed tothe de novo synthesis of biomimetic HDL nanostructures (HDL NPs), and anevaluation of their ability to deliver targeted gene regulatoryoligonucleotides (e.g., cholesterylated oligonucleotides) to the cellcytoplasm. Cancer cells are dependent upon cholesterol delivery by HDLin order to maintain cell membrane biosynthesis and integrity. Thus, acellular model of androgen insensitive prostate cancer (PC3) wasemployed for these studies. Data demonstrate that HDL AuNPs withsurface-adsorbed cholesterylated antisense DNA (chol-DNA-HDL AuNPs)effectively deliver targeted chol-DNA to the cell cytoplasm, avoidendosomal sequestration, and regulate a model RNA target. The bottom-upsynthesis of chol-DNA-HDL AuNPs provides a biomimetic platform foreffective cellular NA delivery.

In another set of embodiments, the present invention is generallydirected to therapeutic agents for the treatment of atherosclerosis andother indications. The therapeutic agent, in one set of embodiments,targets cells such as macrophages (cholesterol uptake and inflammation)and hepatocytes (production of cholesterol-rich low density lipoprotein(LDL)). Certain embodiments are directed to hybrid nanoparticle-basedhigh density lipoprotein mimetic structures (e.g., HDL NPs). The agentmay be used as a cholesterol scavenger (targeting macrophages) and/or asa gene-regulating therapeutic (targeting hepatocytes). In someembodiments, the surface of the HDL NPs may be tailored with nucleicacids, for example, siRNA (e.g., to regulate targeted gene expression inhepatocytes). In addition to mimicking the activity of natural HDL withregard to enhancing reverse cholesterol transport, such structures mayreduce the production of low density lipoprotein (LDL) in hepatocytesthrough HDL NP mediated delivery of siRNA targeting the production ofapolipoprotein B-100 (Apo B-100), the main structural protein of LDL.

Current approaches to therapeutic gene regulation with oligonucleotide(e.g., DNA or siRNA) functionalized AuNPs demonstrate that thenanoparticles are taken up by cells through energy-dependentendocytosis. The consequence of this process is that many of thenanoparticles may be trapped in endosomes and do not maximallyconcentrate in the cytoplasm. For therapeutic approaches that requireconjugate nanostructures to interact with targeted and pathologicallyup-regulated intracellular mRNA targets, for example, this can serve tolimit therapeutic efficacy. As such, one problem addressed by thestructures described herein is the sub-cellular localization of thestructures. The structures may be used to deliver nucleic acids to thecytoplasm within cells to achieve high gene regulating capacity.

Previous research using phospholipid vesicles, or liposomes, have shownthat phospholipids are effective drug delivery agents. In some cases,liposomes are able to permeate through cell membranes. However, studieshave also shown that these phospholipid particles (about 100 nm indiameter) pass through the cell membrane generating temporary holes inthe cell membrane, which can be cytotoxic. In some embodiments by usingstructures described herein, this cytotoxicity may be reduced oravoided. These structures may, in some cases, permeate the cell membraneand avoid endosomal sequestration. In some embodiments in which thestructures include both nucleic acids and lipids, interactions withcells can be tailored by optimizing the nucleic acid:lipid ratio of thestructures and by rationally tailoring the surface chemistry of thestructures.

Although much of the description herein refers to structures acting asbiomimetics of high density lipoprotein, the articles and methodsdescribed herein may be useful for forming mimetics of other entities,including naturally-occurring entities, that may provide sometherapeutic, diagnostic, and/or other beneficial effect. Structures thatmimic naturally-occurring entities may be used to target specific celltypes to treat or diagnose certain indications. Some such biomimeticstructures may include nucleic acids, and may be used for nucleic aciddelivery, tailored nucleic acid release, and/or can be used to regulategene expression in the target.

The illustrative embodiment of FIG. 1 includes a structure 10 having acore 16 and a shell 20 surrounding the core. In embodiments in which thecore is a nanostructure, the core includes a surface 24 to which one ormore components can be optionally attached. For instance, in some cases,core 16 is a nanostructure surrounded by shell 20, which includes aninner surface 28 and an outer surface 32. The shell may include one ormore components 34, such as a plurality of lipids, which may optionallyassociate with one another and/or with surface 24 of the core. Structure10 may optionally include one or more components 36, such as a proteinor other entity, and optionally one or more nucleic acids 37 and 38(e.g., oligonucleotides), which may be used for nucleic acid deliveryand/or to regulate gene expression in a sample or patient in someembodiments. As shown illustratively in FIG. 1, nucleic acid 37 may beadsorbed (e.g., physisorbed) to a portion of the shell and nucleic acid38 may be covalently or near-covalently bonded to surface 24 of theshell.

Components 34 (e.g., lipids) may be associated with the core by beingcovalently attached to the core, physisorbed, chemisorbed, or attachedto the core through ionic interactions, hydrophobic and/or hydrophilicinteractions, electrostatic interactions, van der Waals interactions, orcombinations thereof. In one particular embodiment, the core includes agold nanostructure and the shell is attached to the core through agold-thiol bond. Optionally, components 34 can be crosslinked to oneanother. Crosslinking of components of a shell can, for example, allowthe control of transport of species into the shell, or between an areaexterior to the shell and an area interior of the shell. For example,relatively high amounts of crosslinking may allow certain small, but notlarge, molecules to pass into or through the shell, whereas relativelylow or no crosslinking can allow larger molecules to pass into orthrough the shell. Additionally, the components forming the shell may bein the form of a monolayer or a multilayer, which can also facilitate orimpede the transport or sequestering of molecules. In one exemplaryembodiment, shell 20 includes a lipid bilayer that is arranged tosequester cholesterol.

It should be understood that a shell which surrounds a core need notcompletely surround the core, although such embodiments may be possible.For example, the shell may surround at least 50%, at least 60%, at least70%, at least 80%, at least 90%, or at least 99% of the surface area ofa core. In some cases, the shell substantially surrounds a core. Inother cases, the shell completely surrounds a core. The components ofthe shell may be distributed evenly across a surface of the core in somecases, and unevenly in other cases. For example, the shell may includeportions (e.g., holes) that do not include any material in some cases.If desired, the shell may be designed to allow penetration and/ortransport of certain molecules and components into or out of the shell,but may prevent penetration and/or transport of other molecules andcomponents into or out of the shell. The ability of certain molecules topenetrate and/or be transported into and/or across a shell may dependon, for example, the packing density of the components forming the shelland the chemical and physical properties of the components forming theshell. As described herein, the shell may include one layer of material(e.g., a monolayer), or multilayers of materials in some embodiments.

Structure 10 may also include one or more components 36 such asproteins, nucleic acids, and bioactive agents which may optionallyimpart specificity to the structure. One or more components 36 may beassociated with the core, the shell, or both; e.g., they may beassociated with surface 24 of the core, inner surface 28 of the shell,outer surface 32 of the shell, and/or embedded in the shell. Forexample, one or more components 36 may be associated with the core, theshell, or both through covalent bonds, physisorption, chemisorption, orattached through ionic interactions, hydrophobic and/or hydrophilicinteractions, electrostatic interactions, van der Waals interactions, orcombinations thereof. In one particular embodiment, shell 20 is in theform of a lipoprotein assembly or structure which includes both proteinsand lipids that are covalently or non-covalently bound to one another.For example, the shell may be in the form of an apolipoprotein assemblythat serves as an enzyme co-factor, receptor ligand, and/or lipidtransfer carrier that regulates the uptake of lipids. As describedherein, the components of structure 10 may be chosen such that thesurface of the structure mimics the general surface composition of HDL,LDL, or other structures, and may be used to sequester cholesterol orother structures in some embodiments.

In one set of embodiments, the structures includes one or more nucleicacid 37 and/or 38 (e.g., an oligonucleotide) that may be adapted andarranged to regulate gene expression in a sample or subject, asdescribed in more detail below.

It should be understood that components and configurations other thanthose described herein may be suitable for certain structures andcompositions, and that not all of the components shown in FIG. 1 arenecessarily present in some embodiments.

FIGS. 2A and 2B show general approaches for fabricating certainstructures described herein. The structures may be used, in someembodiments, to both sequester cholesterol and to deliver nucleic acidsand/or to regulate gene expression in a sample or patient. Specifically,FIG. 2A shows a structure 11 that includes a shell 20 and adsorption(e.g., physisorption) of nucleic acids 37 (e.g., oligonucleotides) ontoa portion of the shell. The nucleic acid may be adsorbed to an innerportion, outer portion, interior portion of the shell and/orcombinations thereof. In some embodiments, nucleic acid 37 is anoligonucleotide adapted to regulate gene expression in a sample orpatient.

As shown illustratively in FIG. 2A, structure 11 may include a core 16substantially surrounded by shell 20. The shell may include a firstlayer formed of components 34A and a second layer formed of components34B. In some embodiments, components 34A and/or 34B are lipids, such asphospholipids or other entities described herein. In other embodiments,components 34A and/or 34B are components other than lipids, as describedin more detail below. Structure 11 also includes one or more components36 (e.g., a protein such as an apolipoprotein) associated with theshell. In some embodiments, components 36 are first introduced to core16, which may be a nanostructure core, followed by components 34A and34B which form the shell of structure 11. Component 36 may firstassociate with the surface of the core (e.g., by absorption or by otherinteractions), and in some cases, may associate with a portion, but notall of, the surface of the core. The addition of components 34A and/or34B may displace portions of component 36 from the surface of the core,and/or may associate with portions of the core surface where portions ofcomponent 36 are not present. Structure 11 may be formed by the additionof one or more nucleic acids 37, which may associate with an outercomponent 34B of the shell, with an inner component 34A of the shell,between the inner and outer components, or combinations thereof.

FIG. 2B shows a method for forming a structure 12 that includes one ormore nucleic acids 38 (e.g., oligonucleotides) that are covalently ornear-covalently attached to a surface of a core. The nucleic acid may beattached to the surface of the core directly, or via an interveninglayer (e.g., a passivating layer). In some embodiments, nucleic acid 38is an oligonucleotide adapted to regulate gene expression in a sample orpatient. A method of fabricating structure 12 may include, for example,introducing one or more components 36 (e.g., a protein such as anapolipoprotein) to a core 16. Component 36 may, in some embodiments,associate with a portion, but not all of the surface of the core. Theresulting entity may then be subjected to a nucleic acid 38 that isend-modified with a functional group that allows it to associate withthe surface of the core. The resulting entity may then be subjected tocomponents 34A and/or 34B, which, in some embodiments, may displace atleast a portion of component 36 from the surface of the core, and/or mayassociate with portions of the core surface where portions of component36 are not present.

FIG. 3 shows a method for forming structures 13 which includes a core 16surrounded by a shell 20 that includes a lipid bilayer and a protein 46,such as apolipoprotein A1, embedded in the lipid bilayer. Structure 13may be a biomimetic of endogenous high density lipoprotein (e.g., interms of shape, size and surface chemistry) in some embodiments.Specific examples of components that can be used to form the lipidbilayer include phospholipids 44A and 44B. One or more oligonucleotides47, which may be used to regulate gene expression in a sample orpatient, can be absorbed onto a portion of the shell. Although specificcomponents 46 (e.g., APO-A1), 44A and 44B (e.g., phospholipids), and 47(e.g., oligonucleotides) are shown, other components can be used inother embodiments. Examples of such components are provided in moredetail herein.

It should be understood that compositions and methods described hereinfor treating a sample or patient, especially those for deliveringnucleic acids and/or for regulating gene expression, may involve the useof any suitable structure or combination of structures, whether thenucleic acids are adsorbed onto a portion of the structure orcovalently/near-covalently attached to a portion of the structure. Incertain embodiments, nucleic acids adsorbed to a surface of thestructure core, e.g., regardless of the binding constant, are morelikely to passively diffuse or exchange from the surface of thestructure compared to embodiments in which the nucleic acid isend-modified with suitable groups for covalent or near-covalent couplingto a surface of the structure. As such, in some embodiments, methodsinvolving covalent or near-covalent attachment of nucleic acids mayallow for the particle surface chemistry to be more easily controlled.Furthermore, in some cases, the addition of structures having adsorbednucleic acids into serum-containing matrices (cell culture or blood) mayresult in transfer of the adsorbed nucleic acid from the structure toother serum lipoproteins or albumin Covalent or near covalent couplingof the nucleic acid to a surface of the structure may, in someembodiments, provide for a more stable structures with regard to nucleicacid retention. In other embodiments where it is desirable to releasenucleic acids from the structure to its surrounding environment,structures including adsorbed nucleic acids may be used.

FIG. 4 shows a method for fabricating structures having a mixed layer ofcomponents. Shell 20 includes components 54A and 54B which form a singlelayer (e.g., a monolayer) on the surface of core 16. Examples ofspecific chemical compounds that can be used as components 54A and 54Bare shown in the figure. As shown illustratively in FIG. 4, component54A may be a phospholipid that imparts hydrophobicity to the outersurface of the core. Such components may lie adjacent components 54B,which may include a functional group that can allow attachment of one ormore bioactive agents such as a nucleic acid 57 (e.g., anoligonucleotide such as the one shown specifically in the figure).Although specific chemical compounds are shown in the figure, it shouldbe understood that this is by way of example only, and that otherchemical compounds can be used as components 54A, 54B, and 57 in otherembodiments.

A core, such as core 16 shown in FIGS. 1-4 (e.g., a nanostructure coreor a core that is at least partially hollow), may have any suitableshape and/or size. For instance, the core may be substantiallyspherical, non-spherical, oval, rod-shaped, pyramidal, cube-like,disk-shaped, wire-like, or irregularly shaped. The core may have alargest cross-sectional dimension (or, sometimes, a smallestcross-section dimension) of, for example, less than or equal to about500 nm, less than or equal to about 250 nm, less than or equal to about100 nm, less than or equal to about 75 nm, less than or equal to about50 nm, less than or equal to about 40 nm, less than or equal to about 35nm, less than or equal to about 30 nm, less than or equal to about 25nm, less than or equal to about 20 nm, less than or equal to about 15nm, less than or equal to about 10 nm, or less than or equal to about 5nm. In some cases, the core has an aspect ratio of greater than about1:1, greater than 3:1, or greater than 5:1. In other cases, the core hasan aspect ratio of less than about 10:1, less than 5:1, or less than3:1. As used herein, “aspect ratio” refers to the ratio of a length to awidth, where length and width measured perpendicular to one another, andthe length refers to the longest linearly measured dimension.

A nanostructure core may be formed from any suitable material. Forinstance, in one embodiment, a nanostructure core comprises an inorganicmaterial. The inorganic material may include, for example, a metal(e.g., Ag, Au, Pt, Fe, Cr, Co, Ni, Cu, Zn, Ti, Pd and other metals), asemiconductor (e.g., Rh, Ge, silicon, silicon compounds and alloys,cadmium selenide, cadmium sulfide, indium arsenide, and indiumphosphide), or an insulator (e.g., ceramics such as silicon oxide). Theinorganic material may be present in the core in any suitable amount,e.g., at least 1 wt %, 5 wt %, 10 wt %, 25 wt %, 50 wt %, 75 wt %, 90 wt%, or 99 wt %. In one embodiment, the core is formed of 100 wt %inorganic material. The nanostructure core may, in some cases, be in theform of a quantum dot, a carbon nanotube, a carbon nanowire, or a carbonnanorod. In some cases, the nanostructure core comprises, or is formedof, a material that is not of biological origin. In some embodiments, ananostructure includes one or more organic materials such as a syntheticpolymer and/or a natural polymer. Examples of synthetic polymers includenon-degradable polymers such as polymethacrylate and degradable polymerssuch as polylactic acid, polyglycolic acid and copolymers thereof.Examples of natural polymers include hyaluronic acid, chitosan, andcollagen. In certain embodiments, the nanostructure core does notinclude a polymeric material (e.g., it is non-polymeric).

The surface of the nanostructure core may include the material used toform the interior portions of the core, or the surface of thenanostructure core may be passivated by one or more chemicals tofacilitate attachment of components (e.g., components that form ashell).

In some cases, core 16 is hollow and therefore does not include ananostructure core. Thus, in some such and other embodiments, structure10 includes a shell that can optionally allow components (e.g.,bioactive agents, cholesterol) to pass to and from core 16 and anenvironment 40 outside of the shell. In contrast to certain existinghollow structures (e.g., liposomes) which typically have a largestcross-sectional dimension of greater than about 100 nm due to the sterichindrance of the components forming the shell, structures 10 having ahollow core (e.g., a partially or wholly hollow core) may be very small,e.g., having a largest cross-sectional dimension of less than about 100nm, or even less than about 50 nm. For example, liposomes that include alipid bilayer comprising phospholipids are difficult to fabricate havinga size of less than 100 nm since the phospholipids become limitedsterically, thus making it difficult or impossible to form bilayeredhollow structures with small radii of curvature. Using a nanostructurecore as a template for phospholipids or other molecules, and thenremoving the nanostructure core, may result in hollow or at leastpartially hollow structures with small radii of curvature. Examples ofmethods that can used to form hollow cores are described in more detailin International Patent Publication No. WO/2009/131704, filed Apr. 24,2009 and entitled, “Nanostructures Suitable for Sequestering Cholesteroland Other Molecules, which is incorporated herein by reference in itsentirety for all purposes.

Structures described herein, which may include a shell surrounding acore, may also have any suitable shape and/or size. For instance, astructure may have a shape that is substantially spherical, oval,rod-shaped, pyramidal, cubed-like, disk-shaped, or irregularly shaped.The largest cross-sectional dimension (or, sometimes, a smallestcross-section dimension) of a structure may be, for example, less thanor equal to about 500 nm, less than or equal to about 250 nm, less thanor equal to about 100 nm, less than or equal to about 75 nm, less thanor equal to about 50 nm, less than or equal to about 40 nm, less than orequal to about 35 nm, less than or equal to about 30 nm, less than orequal to about 25 nm, less than or equal to about 20 nm, less than orequal to about 15 nm, or less than or equal to about 5 nm. The structuremay also have an aspect ratio substantially similar to the aspect ratioof the core.

A shell of a structure can have any suitable thickness. For example, thethickness of a shell may be at least 10 Angstroms, at least 0.1 nm, atleast 1 nm, at least 2 nm, at least 5 nm, at least 7 nm, at least 10 nm,at least 15 nm, at least 20 nm, at least 30 nm, at least 50 nm, at least100 nm, or at least 200 nm (e.g., from the inner surface to the outersurface of the shell). In some cases, the thickness of a shell is lessthan 200 nm, less than 100 nm, less than 50 nm, less than 30 nm, lessthan 20 nm, less than 15 nm, less than 10 nm, less than 7 nm, less than5 nm, less than 3 nm, less than 2 nm, or less than 1 nm (e.g., from theinner surface to the outer surface of the shell). The shell may have acombination of the above-noted ranges.

Those of ordinary skill in the art are familiar with techniques todetermine sizes of structures and particles. Examples of suitabletechniques include dynamic light scattering (DLS) (e.g., using a MalvernZetasizer instrument), transmission electron microscopy, scanningelectron microscopy, electroresistance counting and laser diffraction.Other suitable techniques are known to those or ordinary skill in theart. Although many methods for determining sizes of nanostructures areknown, the sizes described herein (e.g., largest or smallestcross-sectional dimensions, thicknesses) refer to ones measured bydynamic light scattering.

The shell of a structure described herein may comprise any suitablematerial, such as a hydrophobic material, a hydrophilic material, and/oran amphiphilic material. Although the shell may include one or moreinorganic materials such as those listed above for the nanostructurecore, in many embodiments the shell includes an organic material such asa lipid or certain polymers.

The components of a shell may be charged in some cases, e.g., to imparta charge on the surface of the structure. In other cases, the componentsof a shell or the surface of the structure is uncharged. The surfacecharge of a structure may be measured by its zeta potential. In somecases, a structure has a zeta potential of, for example, between −2 mVand +2 mV, between −5 mV and +5 mV, between −7 mV and +7 mV, between −10mV and +10 mV, between −20 mV and +20 mV, between −30 mV and +30 mV,between −40 mV and +40 mV, between −50 mV and +50 mV, between −60 mV and+60 mV, between 0 mV and ±5 mV, between ±10 mV and ±30 mV, between ±30mV and ±40 mV, between ±40 mV and ±60 mV, or between ±60 mV and ±80 mV.In some cases, the zeta potential of a structure described herein isless than or equal to −2 mV, less than or equal to −5 mV, less than orequal to −7 mV, less than or equal to −10 mV, less than or equal to −20mV, less than or equal to −30 mV, less than or equal to −40 mV, lessthan or equal to −50 mV, or less than or equal to −60 mV. In otherembodiments, the zeta potential of a structure described herein is +2 mVor greater, +5 mV or greater, +7 mV or greater, +10 mV or greater, +20mV or greater, +30 mV or greater, +40 mV or greater, +50 mV or greater,or +60 mV or greater. Other values of zeta potential are also possible.

In one set of embodiments, a structure described herein or a portionthereof, such as a shell of a structure, includes one or more natural orsynthetic lipids or lipid analogs (i.e., lipophilic molecules). One ormore lipids and/or lipid analogues may form a single layer or amulti-layer (e.g., a bilayer) of a structure. In some instances wheremulti-layers are formed, the natural or synthetic lipids or lipidanalogs interdigitate (e.g., between different layers). Non-limitingexamples of natural or synthetic lipids or lipid analogs include fattyacyls, glycerolipids, glycerophospholipids, sphingolipids,saccharolipids and polyketides (derived from condensation of ketoacylsubunits), sterol lipids and prenol lipids (derived from condensation ofisoprene subunits), fatty acids (e.g., tri-, di-, and monoglycerides),sterol-containing metabolites (e.g., cholesterol), and derivativesthereof.

In one particular set of embodiments, a structure described hereinincludes one or more phospholipids. The one or more phospholipids mayinclude, for example, phosphatidylcholine, phosphatidylglycerol,lecithin, β, γ-dipalmitoyl-α-lecithin, sphingomyelin,phosphatidylserine, phosphatidic acid,N-(2,3-di(9-(Z)-octadecenyloxy))-prop-1-yl-N,N,N-trimethylam moniumchloride, phosphatidylethanolamine, lysolecithin,lysophosphatidylethanolamine, phosphatidylinositol, cephalin,cardiolipin, cerebrosides, dicetylphosphate,dioleoylphosphatidylcholine, dipalmitoylphosphatidylcholine,dipalmitoylphosphatidylglycerol, dioleoylphosphatidylglycerol,palmitoyl-oleoyl-phosphatidylcholine, di-stearoyl-phosphatidylcholine,stearoyl-palmitoyl-phosphatidylcholine,di-palmitoyl-phosphatidylethanolamine,di-stearoyl-phosphatidylethanolamine, di-myrstoyl-phosphatidylserine,di-oleyl-phosphatidylcholine,1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol, and combinationsthereof. In some cases, a shell (e.g., a bilayer) of a structureincludes 50-200 natural or synthetic lipids or lipid analogs (e.g.,phospholipids). For example, the shell may include less than about 500,less than about 400, less than about 300, less than about 200, or lessthan about 100 natural or synthetic lipids or lipid analogs (e.g.,phospholipids), e.g., depending on the size of the structure. In certainembodiments, a structure described herein includes one or morephospholipids that resemble those found in endogenous HDLs.

Non-phosphorus containing lipids may also be used such as stearylamine,docecylamine, acetyl palmitate, and fatty acid amides. In otherembodiments, other lipids such as fats, oils, waxes, sterols, andfat-soluble vitamins (e.g., vitamins A, D, E and K) can be used to formportions of a structure described herein.

A portion of a structure described herein such as a shell or a surfaceof a nanostructure may optionally include one or more alkyl groups,e.g., an alkane-, alkene-, or alkyne-containing species, that optionallyimparts hydrophobicity to the structure. An “alkyl” group refers to asaturated aliphatic group, including a straight-chain alkyl group,branched-chain alkyl group, cycloalkyl (alicyclic) group, alkylsubstituted cycloalkyl group, and cycloalkyl substituted alkyl group.The alkyl group may have various carbon numbers, e.g., between C₂ andC₄₀, and in some embodiments may be greater than C₅, C₁₀, C₁₅, C₂₀, C₂₅,C₃₀, or C₃₅. In some embodiments, a straight chain or branched chainalkyl may have 30 or fewer carbon atoms in its backbone, and, in somecases, 20 or fewer. In some embodiments, a straight chain or branchedchain alkyl may have 12 or fewer carbon atoms in its backbone (e.g.,C₁-C₁₂ for straight chain, C₃-C₁₂ for branched chain), 6 or fewer, or 4or fewer. Likewise, cycloalkyls may have from 3-10 carbon atoms in theirring structure, or 5, 6 or 7 carbons in the ring structure. Examples ofalkyl groups include, but are not limited to, methyl, ethyl, propyl,isopropyl, cyclopropyl, butyl, isobutyl, tert-butyl, cyclobutyl, hexyl,cyclohexyl, and the like.

The alkyl group may include any suitable end group, e.g., a thiol group,a silane group, an amino group (e.g., an unsubstituted or substitutedamine), an amide group, an imine group, a carboxyl group, or a sulfategroup, which may, for example, allow attachment of a ligand to ananostructure core directly or via a linker. For example, where inertmetals are used to form a nanostructure core, the alkyl species mayinclude a thiol group to form a metal-thiol bond. In some instances, thealkyl species includes at least a second end group. For example, thespecies may be bound to a hydrophilic moiety such as polyethyleneglycol. In other embodiments, the second end group may be a reactivegroup that can covalently attach to another functional group (e.g., acarboxylic acid that allows attachment of a bioactive agent such as anucleic acid). In some instances, the second end group can participatein a ligand/receptor interaction (e.g., biotin/streptavidin).

In some embodiments, the shell includes a polymer. For example, anamphiphilic polymer may be used. The polymer may be a diblock copolymer,a triblock copolymer, etc., e.g., where one block is a hydrophobicpolymer and another block is a hydrophilic polymer. For example, thepolymer may be a copolymer of an α-hydroxy acid (e.g., lactic acid) andpolyethylene glycol. In some cases, a shell includes a hydrophobicpolymer, such as polymers that may include certain acrylics, amides andimides, carbonates, dienes, esters, ethers, fluorocarbons, olefins,sytrenes, vinyl acetals, vinyl and vinylidene chlorides, vinyl esters,vinyl ethers and ketones, and vinylpyridine and vinylpyrrolidonespolymers. In other cases, a shell includes a hydrophilic polymer, suchas polymers including certain acrylics, amines, ethers, styrenes, vinylacids, and vinyl alcohols. The polymer may be charged or uncharged. Asnoted herein, the particular components of the shell can be chosen so asto impart certain functionality to the structures.

Where a shell includes an amphiphilic material, the material can bearranged in any suitable manner with respect to the core and/or witheach other. For instance, the amphiphilic material may include ahydrophilic group that points towards the core and a hydrophobic groupthat extends away from the core, or, the amphiphilic material mayinclude a hydrophobic group that points towards the core and ahydrophilic group that extends away from the core. Bilayers of eachconfiguration can also be formed.

In some cases, the components that form a shell of a structure describedherein are chosen, at least in part, on the molecular weight of thecomponent. In some cases, the shell comprises, or is substantiallyformed of, a component having a molecular weight of, for example, lessthan or equal to 50,000 g/mol, less than or equal to 25,000 g/mol, lessthan or equal to 15,000 g/mol, less than or equal to 10,000 g/mol, lessthan or equal to 7,000 g/mol, less than or equal to 5,000 g/mol, lessthan or equal to 2,000 g/mol, less than or equal to 1,000 g/mol, or lessthan or equal to 500 g/mol. In other embodiments, the molecular weightof a component is 1,000 g/mol or greater, 2,000 g/mol or greater, 5,000g/mol or greater, 7,000 g/mol or greater, 10,000 g/mol or greater,15,000 g/mol or greater, 25,000 g/mol or greater, or 50,000 g/mol orgreater. The component may be in the form of a polymer or a non-polymer(e.g., a lipid), such as those described herein.

In certain embodiments, a structure comprises a shell including a mixedlayer (e.g., mixed monolayer) of components. For example, in oneembodiment, the shell may include at least two types of lipids (e.g., afirst lipid and a second lipid) such as those described herein, whichform a mixed layer (e.g., a monolayer). In some embodiments includingcertain structures having a shell comprising a bilayer configuration, atleast one of the layers may include a mixture of first and secondcomponents. In one set of embodiments, the shell may include a lipidsuch as those described herein (e.g., a first component), and a compoundincluding an alkyl group such as those described herein (e.g., a secondcomponent) that can be attached to a nanostructure core, and the twocomponents may form a mixed layer (e.g., monolayer). The alkyl group mayhave various carbon numbers, e.g., between C₂ and C₄₀, and mayoptionally have attached to it one or more suitable end groups, e.g., athiol group, a silane group, an amino group (e.g., an unsubstituted orsubstituted amine), an amide group, an imine group, a carboxyl group, ora sulfate group, which may, for example, allow attachment of the groupto a nanostructure core directly or via a linker. In some cases, one ofthe components in a mixed layer includes one end for attachment to ananostructure core, and a second end for attachment to a bioactive agentsuch as a nucleic acid. Other types of components can also be includedin a mixed layer of a shell. In certain embodiments, a mixed layer mayinclude 3 or more, or 4 or more different components that form thelayer. In some cases, the mixed layer is a self-assembled monolayer.

In embodiments in which there are 2 or more components that form alayer, each component may be present in the layer in an amount of, forexample, at least 5%, at least 10%, at least 20%, at least 30%, at least40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least90% of the layer by weight. For instance, in a 2-component system, thepercentage of a first component relative to the total amount of firstand second components in a mixed layer (by weight) may be, for example,at least 5%, at least 10%, at least 20%, at least 30%, at least 40%, atleast 50%, at least 60%, at least 70%, at least 80%, or at least 90%. Inother embodiments, in a 2-component system, the percentage of a firstcomponent relative to the total number of first and second components ina mixed layer may be, for example, at least 5%, at least 10%, at least20%, at least 30%, at least 40%, at least 50%, at least 60%, at least70%, at least 80%, or at least 90%.

In one set of embodiments, the structures described herein areconstructed and arranged to sequester, transport, or exchange certainmolecules to and/or from a subject or a biological sample. Thestructure, which may include one or more nucleic acids, may alsofunction to deliver nucleic acids, release nucleic acids, and/orregulate gene expression in the sample or patient. Thus, certainstructures herein may have multiple functions.

In one set of embodiments, the structures described herein, whetherincluding a nanostructure core or a hollow core, is constructed andarranged to sequester, transport, or exchange certain molecules toand/or from a subject or a biological sample. For instance, whenintroduced into a subject, a structure may interact with one or morecomponents in the subject such as cells, tissues, organs, particles,fluids (e.g., blood), and portions thereof. The interaction may takeplace, at least in part, through the shell of the structure, and mayinvolve, for example, the exchange of materials (e.g., proteins,peptides, polypeptides, nucleic acids, nutrients) from the one or morecomponents of the subject to the structure, and/or from structure to theone or more components of the subject. In some such embodiments, theshell of the structure can be designed to include components withproperties that allow favorable interaction (e.g., binding, adsorption,transport) with the one or more materials from the subject. For example,the shell may include components having a certain hydrophobicity,hydrophilicity, surface charge, functional group, specificity forbinding, and/or density to facilitate particular interactions, asdescribed herein. In certain embodiments, one or more materials from asubject are sequestered by the structure, and the structure mayfacilitate excretion, breakdown, and/or transport of the material. Theexcretion, breakdown, and/or transport of the material can lead tocertain beneficial and/or therapeutic effects. As such, the structuresdescribed herein can be used for the diagnosis, prevention, treatment ormanagement of certain diseases or bodily conditions.

In one particular set of embodiments, a structure described herein isconstructed and arranged to sequester cholesterol (and/or other lipids).Without wishing to be bound by theory, it is hypothesized that certainstructures described herein can sequester cholesterol throughhydrophobic interactions with a hydrophobic layer (e.g., a lipid layersuch as a lipid bilayer) of the structure. For example, in some cases,cholesterol can bind to a surface of the structure (e.g., to the outersurface of the shell) through hydrophobic interactions. In other cases,the cholesterol can be transported from an outer surface of the shell toan inner surface of the shell and/or to the core of the structure. Thecholesterol can also be imbedded in the shell, e.g., between two layersof the shell. Optionally, structures described herein may include one ormore apolipoproteins (e.g., apoliprotein-A1), proteins, or peptides,which may facilitate the sequestering of cholesterol and/or otherlipids. The structures described herein may also sequester cholesterolby removing cholesterol and phospholipids from a cell, or from othercirculating lipoprotein species. Cholesterol sequestered by structuresdescribed herein may, in some embodiments, be esterified enzymatically(e.g., by lecithin:acyl CoA transferase (LCAT)) to form a cholesterylester that may migrate towards the center of the structure. As describedherein, structures that are adapted to sequester cholesterol may alsofunction to deliver nucleic acids and/or regulate gene expression in apatient or sample.

Additionally, without wishing to be bound by theory, it is believed thatcertain structures described herein can sequester cholesterol from highconcentrations of cholesterol (e.g., plaques) and transfer it to theliver directly or indirectly. For example, cholesterol may besequestered from areas of high concentrations of cholesterol (e.g.,plaques) by direct efflux of cholesterol from the plaque, or anycomponents of the plaque, into or onto the structures described herein.In some such embodiments, the cholesterol that is sequestered by thestructures is transported directly to the liver by the structures. Inother embodiments, other circulating lipoprotein species (e.g., LDL) mayparticipate in cholesterol exchange. For example, in some cases, freecholesterol or esterified cholesterol is transferred from otherlipoproteins to the structures described herein. In other cases, oncefree cholesterol or esterified cholesterol is sequestered by thestructures described herein, the cholesterol can be transferred from thestructures to the other lipoprotein species, which may ultimately end upin the liver. Thus, in such embodiments, the structures described hereincan augment reverse cholesterol transport indirectly. Furthermore, inthe case where free cholesterol or esterified cholesterol is sequesteredfrom the structures described herein to other lipoprotein species, thestructures may further sequester cholesterol from, for example, areas ofhigh cholesterol content, plaques, circulating lipoproteins, or otherphysiologic sites of high cholesterol concentration. It should beunderstood, however, that the structures described herein may removecholesterol and/or other molecules by other routes, such as throughurine, and the invention is not limited in this respect. In someembodiments, the structures can sequester cholesterol by these or otherroutes, and may also function to deliver nucleic acids and/or regulategene expression prior, during, or after the sequestering process.

The amount of a molecule (e.g., cholesterol or other lipids) sequesteredby a structure and/or a composition described herein may depend on, forexample, the size of the structure, the biology and surface chemistry ofthe particle, as well as the method of administration. For instance, ifthe structures are circulated indefinitely from the periphery to theliver and out again, relative few cholesterol molecules need to besequestered by each structure in order for the composition to beeffective, since the structures are recycled. On the other hand, if acomposition is used, for example, as a cholesterol or bile-salt bindingresin orally, each structure may sequester a larger number ofcholesterol to increased cholesterol uptake. Also, if the structures areof a size such that they are rapidly excreted (e.g., through the liveror urine) after sequestering cholesterol, a high uptake of cholesterolper structure, and/or continuous infusion may be implemented. As such, asingle structure described herein, which may be incorporated into apharmaceutical composition or other formulation, may be able tosequester any suitable number of a particular type of molecule (e.g.,lipids such as cholesterol; steroids such as estrogen, progesterone, andtestosterone; bile salts, etc.) during use, e.g., at least 2, at least5, at least 10, at least 20, at least 30, at least 50, at least 100, atleast 200, at least 500, at least 1,000, at least 2,000, at least 5,000,or at least 10,000 molecules, which may depend on the size (e.g.,surface area and/or volume) of the structure, the particularapplication, and the method of administration. In some cases, suchnumbers of molecules can be bound to the structure at one particularinstance.

In some cases, a single structure has a binding constant forcholesterol, K_(d), of, for example, less than or equal to about 50 mM,less than or equal to about 15 mM, less than or equal to about 10 mM,less than or equal to about 5 mM, less than or equal to about 1 mM, lessthan or equal to about 100 μM, less than or equal to about 10 μM, lessthan or equal to about 1 μM, less than or equal to about 0.1 μM, lessthan or equal to about 50 nM, less than or equal to about 15 nM, lessthan or equal to about 10 nM, less than or equal to about 7 nM, lessthan or equal to about 5 nM, less than or equal to about 4 nM, less thanor equal to about 2 nM, less than or equal to about 1 nM, less than orequal to about 0.1 nM, less than or equal to about 10 μM, less than orequal to about 1 μM, less than or equal to about 0.1 μM, less than orequal to about 10 μM, or less than or equal to about 1 μM. In someembodiments, the structures have a binding constant for cholesterol lessthan the concentration of total cholesterol in vivo. In some cases, thetotal cholesterol is the amount of circulating cholesterol. In certainembodiments, the structures have a binding constant for cholesterolsubstantially similar to that of endogenous HDL. Methods for determiningthe amount of cholesterol sequestered and binding constants are providedin more detail below.

In certain embodiments, the molecules that are sequestered by thestructures described herein cause the structure to grow in size (e.g.,cross-sectional area, surface area and/or volume), e.g., depending onthe number of molecules sequestered. The molecules may associate with asurface of a structure, be imbedded in a shell of a structure, betransported to a core of the structure, or combinations thereof, asdescribed herein. As such, the size of a structure (e.g.,cross-sectional area, surface area and/or volume) can increase by atleast 5%, at least 10%, at least 20%, at least 30%, at least 50%, atleast 70%, or at least 100%, from a time prior to sequestration comparedto a time after/during sequestration in some embodiments.

It should be understood, however, that while many of the embodimentsherein are described in the context of sequestering cholesterol or otherlipids, the invention is not limited as such and the structures,compositions, kits, and methods described herein may be used tosequester other molecules and/or to prevent, treat, or manage otherdiseases or bodily conditions, optionally in combination with nucleicacid delivery and/or gene regulation.

As described herein, the structures described herein may optionallyinclude one or more proteins, polypeptides and/or peptides (e.g.,synthetic peptides, amphiphilic peptides). In one set of embodiments,the structures include proteins, polypeptides and/or peptides that canincrease the rate of cholesterol transfer or the cholesterol-carryingcapacity of the structures. The one or more proteins or peptides may beassociated with the core (e.g., a surface of the core or embedded in thecore), the shell (e.g., an inner and/or outer surface of the shell,and/or embedded in the shell), or both. Associations may includecovalent or non-covalent interactions (e.g., hydrophobic and/orhydrophilic interactions, electrostatic interactions, van der Waalsinteractions).

An example of a suitable protein that may associate with a structuredescribed herein is an apolipoprotein, such as apolipoprotein A (e.g.,apo A-I, apo A-II, apo A-IV, and apo A-V), apolipoprotein B (e.g., apoB48 and apo B100), apolipoprotein C (e.g., apo C-I, apo C-II, apo C-III,and apo C-IV), and apolipoproteins D, E, and H. Specifically, apo A₁,apo A₂, and apo E promote transfer of cholesterol and cholesteryl estersto the liver for metabolism and may be useful to include in structuresdescribed herein. Additionally or alternatively, a structure describedherein may include one or more peptide analogues of an apolipoprotein,such as one described above. A structure may include any suitable numberof, e.g., at least 1, 2, 3, 4, 5, 6, or 10, apolipoproteins or analoguesthereof. In certain embodiments, a structure includes 1-6apolipoproteins, similar to a naturally occurring HDL particle. Ofcourse, other proteins (e.g., non-apolipoproteins) can also be includedin structures described herein.

In certain embodiments, structures describe herein may exhibit a bindingaffinity to macrophages and hepatocytes substantially equal to thebinding affinity of endogenous HDL. In some cases, the structuresdescribed herein comprises a density of an apolipoprotein (e.g., ApoA-1) that is within 30%, within 20%, or within 10% of the density of theapolipoprotein on endogenous HDL.

Optionally, one or more enzymes may also be associated with a structuredescribed herein. For example, lecithin-cholesterol acyltransferase isan enzyme which converts free cholesterol into cholesteryl ester (a morehydrophobic form of cholesterol). In naturally-occurring lipoproteins(e.g., HDL and LDL), cholesteryl ester is sequestered into the core ofthe lipoprotein, and causes the lipoprotein to change from a disk shapeto a spherical shape. Thus, structures described herein may includelecithin-cholesterol acyltransferase to mimic HDL and LDL structures.Other enzymes such as cholesteryl ester transfer protein (CETP) whichtransfers esterified cholesterol from HDL to LDL species may also beincluded.

In some cases, one or more bioactive agents are associated with astructure or a composition described herein. The one or more bioactiveagents may optionally be released from the structure or composition(e.g., long-term or short-term release). Bioactive agents includemolecules that affect a biological system and include, for exampleproteins, nucleic acids, therapeutic agents, vitamins and theirderivatives, viral fractions, lipopolysaccharides, bacterial fractionsand hormones. Other agents of interest may include chemotherapeuticagents, which are used in the treatment and management of cancerpatients. Such molecules are generally characterized asantiproliferative agents, cytotoxic agents and immunosuppressive agentsand include molecules such as taxol, doxorubicin, daunorubicin,vinca-alkaloids, actinomycin and etoposide.

Other examples of bioactive agents include cardiovascular drugs,respiratory drugs, sympathomimetic drugs, cholinomimetic drugs,adrenergic or adrenergic neuron blocking drugs, analgesics/antipyretics,anesthetics, antiasthmatics, antibiotics, antidepressants,antidiabetics, antifungals, antihypertensives, anti-inflammatories(e.g., glucocorticoids such as prednisone), nucleic acid species (e.g.,anti-sense and siRNA species against inflammatory mediators),antineoplastics, antianxiety agents, immunosuppressive agents,immunomodulatory agents, antimigraine agents, sedatives/hypnotics,antianginal agents, antipsychotics, antimanic agents, antiarrhythmics,antiarthritic agents, antigout agents, anticoagulants, thrombolyticagents, antifibrinolytic agents, hemorheologic agents, antiplateletagents, anticonvuls ants, antiparkinson agents,antihistamines/antipruritics, agents useful for calcium regulation,antibacterials, antivirals, antimicrobials, anti-infectives,bronchodialators, hypoglycemic agents, hypolipidemic agents, agentsuseful for erythropoiesis stimulation, antiulcer/antireflux agents,antinauseants/antiemetics and oil-soluble vitamins, cholesterol agents(e.g., statins such as Lipitor, Zocor, which may be known to lowercholesterol levels), or combinations thereof.

In some embodiments, one or more nucleic acids is associated with astructure described herein. A nucleic acid includes any double strand orsingle strand deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) ofvariable length. Nucleic acids include sense and anti-sense strands.Nucleic acid analogs such as phosphorothioates, phosphoramidates,phosphonates analogs are also considered nucleic acids and may be used.Nucleic acids also include chromosomes and chromosomal fragments.

In some cases, the nucleic acid is an oligonucleotide. A nucleic acid oroligonucleotide may be associated with a structure described herein inany suitable manner (e.g., with the core, a shell, or combinationthereof) as discussed herein. The nucleic acid or oligonucleotide may beadapted and arrange to regulate gene expression in a sample or apatient. Any suitable technique may be used to attach a nucleic acid oran oligonucleotide to a portion of a structure described herein, forinstance, electrostatic adsorption techniques, chemisorption techniques,gold-thiol conjugation chemistry, or the like. In some instances, thenucleic acid or oligonucleotide is covalently or near-covalently bondedto the nanostructure core or to the shell. In other instances, thenucleic acid or oligonucleotide is covalently attached to cholesterol(e.g., 5′-cholesteryl DNA) and associated in any suitable manner with astructure described herein. The nucleic acid or oligonucleotide mayinclude, for example, DNA, RNA, or the like, and may be single strandedor double stranded. In some cases, the nucleic acid or oligonucleotidemay be antisense DNA. Specific examples of RNA include, withoutlimitation, siRNA, mRNA, miRNA, tRNA, etc. In some cases, for example,the RNA may be siRNA or other types of RNA selected to regulate geneexpression in a cell to which the nanoparticle is targeted. In certainembodiments, the nucleic acid or oligonucleotide is synthetic. In somecases, the nucleic acid or oligonucleotide is cholesterylated.

As noted above, a nucleic acid compound or oligonucleotide describedherein may be single or double stranded. A double stranded compound mayalso include regions of overhang or non-complementarity, where one orthe other of the strands is single stranded. A single stranded compoundmay include regions of self-complementarity, meaning that the compoundforms a so-called “hairpin” or “stem-loop” structure, with a region ofdouble helical structure. A nucleic acid or oligonucleotide may comprisea nucleotide sequence that is complementary to a region consisting of nomore than 1000, no more than 500, no more than 250, no more than 100 orno more than 50, 35, 30, 25, 22, 20, 18, 15, 12, 10, 8, 6, 5, 4, or 3nucleotides (nucleotide bases or nucleobases) of the full-length nucleicacid sequence or ligand nucleic acid sequence. The region ofcomplementarity may be at least 8 nucleotides, and optionally at least10 or at least 15 nucleotides, optionally between 15 and 25 nucleotides,or optionally between 3 and 20 nucleotides (e.g., between 3 and 10nucleotides, or between 3 and 10 nucleotides). A region ofcomplementarity may fall within an intron, a coding sequence or anoncoding sequence of the target transcript, such as the coding sequenceportion.

A nucleic acid described herein (which may be associated with ananostructure) may have a length of about 3 to about 1000 nucleotides(nucleotide bases or nucleobases) or base pairs in length, about 3 toabout 700 nucleotides or base pairs in length, about 4 to about 500nucleotides or base pairs in length, about 3 to about 200 nucleotides orbase pairs in length, about 3 to about 150 nucleotides or base pairs inlength, about 3 to about 100 nucleotides or base pairs in length, about3 to about 75 nucleotides or base pairs in length, about 10 to about 50nucleotides or base pairs in length, about 10 to about 40 nucleotides orbase pairs in length, about 10 to about 30 nucleotides or base pairs inlength, about 10 to about 25 nucleotides or base pairs in length, about3 to about 30 nucleotides or base pairs in length, about 3 to about 20nucleotides or base pairs in length, or about 3 to about 10 nucleotidesor base pairs in length. In some embodiments, a nucleic acid includesabout 200 nucleotides or base pairs in length or less, about 150nucleotides or base pairs in length or less, about 100 nucleotides orbase pairs in length or less, about 75 nucleotides or base pairs inlength or less, about 50 nucleotides or base pairs in length or less,about 30 nucleotides or base pairs in length or less, about 25nucleotides or base pairs in length or less, about 20 nucleotides orbase pairs in length or less, about 15 nucleotides or base pairs inlength or less, or about 10 nucleotides or base pairs in length or less.Other lengths are also possible. As described herein, the nucleic acidmay be single stranded in some embodiments, and double stranded in otherembodiments.

In certain embodiments, structures described herein may include veryshort oligonucleotides that can be used to bind a target. For example,microRNAs may bind to 3′-UTRs through “seed sequence” pairings that maybe as short as 3 or 4 bases long.

In certain embodiments, a targeted sequence may have a length such asone described above with respect to a nucleic acid that can beassociated with a structure described herein. For example, a targetedsequence may have a length of about 3 to about 1000 nucleotides inlength, about 3 to about 700 nucleotides in length, about 4 to about 500nucleotides in length, about 3 to about 200 nucleotides in length, about3 to about 150 nucleotides in length, about 3 to about 100 nucleotidesin length, about 3 to about 75 nucleotides in length, about 10 to about50 nucleotides in length, about 10 to about 40 nucleotides in length,about 10 to about 30 nucleotides in length, about 10 to about 25nucleotides in length, about 3 to about 30 nucleotides in length, about3 to about 20 nucleotides in length, or about 3 to about 10 nucleotidesin length. Other lengths are also possible.

A nucleic acid or oligonucleotide may be a DNA (particularly for use asan antisense), RNA or RNA:DNA hybrid. Any one strand may include amixture of DNA and RNA, as well as modified forms that cannot readily beclassified as either DNA or RNA. For example, in some cases, the nucleicacid is single stranded, and is a hybrid of RNA and DNA nucleobases.Likewise, a double stranded compound may be DNA:DNA, DNA:RNA or RNA:RNA,and any one strand may also include a mixture of DNA and RNA, as well asmodified forms that cannot readily be classified as either DNA or RNA.For example, in some cases, the nucleic acid is a duplex with one, orthe other, or both strands made of RNA and DNA nucleobases. The nucleicacid or oligonucleotide associated with a structure described herein maybe recombinant in some embodiments.

The nucleic acid or oligonucleotide associated with a structuredescribed herein may include any of a variety of modifications,including one or modifications to the backbone (the sugar-phosphateportion in a natural nucleic acid, including internucleotide linkages)or the base portion (the purine or pyrimidine portion of a naturalnucleic acid). For example, in some cases one or more of the nucleobasesused to fabricate the nucleic acid are modified with certain chemicalmoieties such as, for example, phosphorthioate, morpholino, 2′-F, and2′-OMe. In some embodiments, the nucleic acid is modified with afluorophore, or other imaging agent (e.g., gadolinium, radionuclide).For example, the nucleic acid may include a fluorophore that is adaptedto change in fluorescence intensity upon binding to a target protein ora small molecule. In another example, an antisense nucleic acid compoundmay, in some embodiments, have a length of about 3 to about 30nucleotides and may contain one or more modifications to improvecharacteristics such as stability in the serum, in a cell or in a placewhere the compound is likely to be delivered. In the case of an RNAiconstruct, the strand complementary to the target transcript may be RNAor modifications thereof. The other strand may be RNA, DNA or any othervariation. The duplex portion of double stranded or single stranded“hairpin” RNAi construct may have a length of, for example, 18 to 40nucleotides in length and optionally about 20 to 30 nucleotides inlength for example. Catalytic or enzymatic nucleic acids may, in somecases, be ribozymes or DNA enzymes and may also contain modified forms.

In certain embodiments, nucleic acid or oligonucleotide associated witha structure described herein is modified with a lipid, such as onedescribed herein. For example, a nucleic acid or oligonucleotide may becholesterylated, e.g., the nucleic acid may comprise a 5′-cholesterylDNA or 3′-cholesteryl DNA.

The nucleic acids or oligonucleotides associated with the structuresdescribed herein can be fabricated using any suitable method, includingthose methods described herein and those known to one of ordinary skillin the art. The nucleic acids or oligonucleotides may optionally bemodified in any suitable manner to facilitate attachment to a portion ofa structure described herein. For example, as noted above, in oneembodiment, a nucleic acid or oligonucleotide, prior to attachment, hasan end modified to include a cholesterol function group. In anotherembodiment, a nucleic acid or oligonucleotide, prior to attachment, hasan end modified to include an alkylthiol. Other modifications are alsopossible such as those described herein.

Nucleic acid compounds and oligonucleotides, when associated with astructure as described herein, may regulate or modulate expression(e.g., inhibit expression) of the target by at least about 50%, at leastabout 60%, at least about 70%, at least about 80%, or at least about 90%when contacted with a biological sample or patient under physiologicalconditions and at a concentration where a nonsense or sense control haslittle or no effect. In some embodiments, nucleic acid compounds andoligonucleotides, when associated with a structure as described herein,may regulate or modulate expression (e.g., inhibit expression) of thetarget by at least about 50% more, at least about 60% more, at leastabout 70% more, at least about 80% more, or at least about 90% more thanthe same nucleic acid compounds and oligonucleotides that are notassociated with structures described herein (e.g., free nucleic acidcompounds and oligonucleotides) when contacted with a biological sampleor patient under physiological conditions.

In some embodiments, certain structures described herein that canregulate gene expression of a target in one or more of the above-notedranges is a structure that mimics endogenous HDL. For instance, thestructure may include a nucleic acid and/or oligonucleotide and a coresubstantially surrounded by a shell comprising a lipid (e.g., aphospholipid) and an apolipoprotein. Such a structure may regulate geneexpression of a target by at least about 50% more, at least about 60%more, at least about 70% more, at least about 80% more, or at leastabout 90% more, when contacted with a biological sample or patient underphysiological conditions, than either 1) a similar structure that mimicsHDL but does not include the nucleic acid compounds and/oroligonucleotides; or, in other embodiments, 2) the same nucleic acidcompounds and/or oligonucleotides associated with a structure that doesnot mimic endogenous HDL.

In some cases, structures described herein, which may include one ormore nucleic acid compounds or oligonucleotides, may have relativelyhigh cellular uptake.

For example, for a composition including a plurality of structures thatis delivered to cells, at least 80%, at least 85%, at least 90%, atleast 95%, at least 97%, or at least 99% of the structures in acomposition may be uptaken by the cells.

In certain embodiments, structures described herein, which may includeone or more nucleic acid compounds or oligonucleotides, may haverelatively low endosomal sequestration (e.g., a relatively highpercentage of the structures may reside in the cytoplasm of the cell)upon delivery of the structures to cells. For example, at least 50%, atleast 60%, at least 70%, at least 80%, at least 85%, at least 90%, atleast 95%, at least 97%, or at least 99% of the structures that enterinto a cell may reside in the cytoplasm of the cell. As describedherein, avoidance of endosomal sequestration may allow the structures tohave a greater therapeutic effect.

It should be understood that the components described herein, such asthe lipids, phospholipids, alkyl groups, polymers, proteins,polypeptides, peptides, enzymes, bioactive agents, nucleic acids, andspecies for targeting described above, may be associated with astructure in any suitable manner and with any suitable portion of thestructure, e.g., the core, the shell, or both. For example, one or moresuch components may be associated with a surface of a core, an interiorof a core, an inner surface of a shell, an outer surface of a shell,and/or embedded in a shell. Furthermore, such components can be used, insome embodiments, to facilitate the exchange and/or transport ofmaterials (e.g., proteins, peptides, polypeptides, nucleic acids,nutrients) from one or more components of a subject (e.g., cells,tissues, organs, particles, fluids (e.g., blood), and portions thereof)to a structure described herein, and/or from the structure to the one ormore components of the subject. In some cases, the components havechemical and/or physical properties that allow favorable interaction(e.g., binding, adsorption, transport) with the one or more materialsfrom the subject.

Additionally, the components described herein, such as the lipids,phospholipids, alkyl groups, polymers, proteins, polypeptides, peptides,enzymes, bioactive agents, nucleic acids, and species for targetingdescribed herein, may be associated with a structure described hereinprior to administration to a subject or biological sample and/or afteradministration to a subject or biological sample. For example, in somecases a structure described herein includes a core and a shell which isadministered in vivo or in vitro, and the structure has a greatertherapeutic effect after sequestering one or more components (e.g., anapolipoprotein) from a subject or biological sample. That is, thestructure may use natural components from the subject or biologicalsample to increase efficacy of the structure after it has beenadministered.

In some embodiments, structures described herein can include a modularnucleic acid component for controlling the release of nucleic acid fromthe structure (e.g., nanostructure core surface) by various stimuli. Thestimuli may include, for example, ex vivo (e.g., light), physiologic(e.g., reducing intracellular environment), or pathologic (e.g.,reactive oxygen species or low pH) triggers. Tuning the properties ofthe structure may also be used to facilitate release of nucleic acidsfrom the structure. For example, portions of the shell (e.g., lipidssuch as phospholipids), charge of the structure (e.g., surface of thestructure), presence and/or absence of proteins, and/or ligands attachedto surface adsorbed nucleic acids (e.g., cholesterol, other lipids,etc.) can be modified, in some embodiments, to facilitate release of anucleic acid from the structure. Nucleic acid triggered releasemechanisms may be used to provide a way to test the mechanism of actionof the structure once inside cells, compare materials with differentrelease chemistries, and/or address bio-nano interfacial challenges(e.g., endosomal sequestration) that may surface after initial testing.

In some embodiments, structures that can be used to release nucleicacids may be fabricated using, for example, Au—S coupling ofoligonucleotides (e.g. DNA) to the surface of the nanostructure core.Example of components that can be used with structures described hereinfor nucleic acid release are described in Example 5 in connection withFIG. 15. In some embodiments, the structure may effectively sequesterthe gene regulating portion of the nucleic acid sequence on the surfaceof the core or within the shell of a structure, and the gene regulatingportion may not be available to the intracellular cytoplasmic machineryrequired to regulate gene expression. For example, the shell of thestructure surrounding the core may prevent or inhibit the nucleic acidfrom being exposed to the intracellular cytoplasmic machinery requiredto regulate gene expression, but the structure may be adapted to releasethe nucleic acid upon triggering. Advantageously, the timing of nucleicacid release can be controlled by such a method. Furthermore, in someembodiments, by sequestering the nucleic acid within the shell of thestructure such that the nucleic acid is not exposed or is minimallyexposed to the surface of the structure, breakdown of the nucleic acidby nucleases can be prevented or reduced. Accordingly, in some cases,nucleic acids and oligonucleotides, when associate with a structure asdescribed herein, may have reduced susceptibility to nucleasedegradation.

In one set of embodiments, a method of treatment includes delivering aplurality of structures described herein to a sample or patient, whereinthe structure includes a shell (e.g., comprising a lipid or otherentity) substantially surrounding a core and an oligonucleotide adaptedto regulate gene expression. The method also includes releasing theoligonucleotide from the structure to the sample or patient, andregulating gene expression in the sample or patient.

In some embodiments, the structures, compositions, and methods describedherein can be used for targeting, such that the structures describedherein can be delivered to specific target sites. Targeting may include,in some embodiments, functionalizing the structure with one or moreligands or receptors specific for a particular target site or sites. Forinstance, a structure described herein may include a ligand for areceptor (or a receptor for a ligand) that is expressed on the surfaceof a site to be targeted. Examples of specific surface componentsinclude antibodies (including antibody fragments and derivatives),plaque markers, specific cell surface markers, small molecules (e.g.,folate), and aptamers, i.e., a nucleic acid able to specifically bind aspecific target molecule, such as a biological moiety (e.g., RNAaptamers and DNA aptamers). Examples of specific targets inatherosclerotic plaques and in vascular endothelial cells in thevicinity of the plaque include but are not limited to: fibrin,macrophages, VCAM-1, E-selectin, integrin [alpha]_(v)[beta]₃, P-selectinand P-selectin glycoprotein ligand-1 (PSGL-1). Furthermore, a proteincomponent of the structures described herein could be modified and usedas the targeting molecule, e.g. Apo E, or Apo A₁. The structures mayalso include certain groups (e.g., asialo groups) for targeting specificsmall molecules.

In one aspect, structures such as those described herein may be targetedto macrophages or hepatocytes, or other immune cells. In one set ofembodiments, for example, structures may be targeted to macrophages forthe treatment of atherosclerosis. For example, the structures may beable to sequester cholesterol from macrophages to treat atherosclerosisand similar conditions implicating cholesterol and/or macrophages. Thestructures may also be adapted to deliver nucleic acids and/or regulategene expression in the sample or patient.

In one set of embodiments, the structures, compositions and methodsdescribed herein are used to diagnose, prevent, treat or manage diseasesor bodily conditions associated with abnormal lipid levels. Forinstance, high density lipoprotein is a dynamic serum nanostructureprotective against the development of atherosclerosis and resultantillnesses such as heart disease and stroke. By administering certaincompositions and methods described herein, such as those includingstructures that mimic naturally occurring HDL, circulating serum HDLlevels (e.g., low HDL levels) may be increased. This can provide apromising therapeutic approach to, for example, preventing andpotentially reversing atherosclerosis by augmenting reverse cholesteroltransport. In other embodiments, compositions and methods describedherein may be used to decrease LDL levels (e.g., decrease high LDLlevels) or temporarily increase LDL levels, e.g., by using structurethat mimics naturally occurring LDL. Furthermore, in certainembodiments, diagnosis, prevention, treatment or management of diseasesor bodily conditions associated with abnormal lipid levels may involveusing the structures, compositions and methods described herein toaugment reverse cholesterol transport (e.g., directly or indirectly) byway of augmenting the flux of cholesterol through and out of the body.Such diagnosis, prevention, treatment, or methods of managing diseasesor bodily conditions may include using the structures to regulate geneexpression of a target and/or to deliver nucleic acids. Accordingly,certain structures described herein may both sequester cholesterol andfunction as a gene-regulating therapeutic.

With consideration given to mortality and world-wide prevalence, thesignificance of atherosclerosis is profound. Atherosclerosis is achronic infiltrative and inflammatory disease of the systemic arterialtree caused by excess circulating cholesterol. Cholesterol is notsoluble in the aqueous milieu of the human body, thus travels by way ofdynamic nanoparticle carriers known as lipoproteins (LPs). The main LPcarriers of cholesterol are low density lipoprotein (LDL) and highdensity lipoprotein (HDL). LDL originates in the liver and highcirculating levels promote atherosclerosis and increase the risk ofcardiovascular disease. Therapeutic LDL lowering has been shown toreduce cardiovascular disease mortality. Conversely, HDL is well-knownto promote reverse cholesterol transport (RCT) from sites of peripheraldeposition (macrophage foam cells) to the liver for excretion.Accordingly, high HDL levels inversely correlate with cardiovasculardisease risk. There is intense interest in therapeutic strategies toharness the beneficial effects of HDL to address the substantialcardiovascular disease burden that exists despite current LDL loweringtherapies. Structures described herein may be used, in some embodiments,to mimic endogenous HDL so as to treat atherosclerosis and to delivernucleic acids and/or regulate gene expression at the same time. Forexample, in one set of embodiments, the structures described herein arecapable of exhibiting the bio-mimetic characteristics of HDL with regardto cholesterol sequestration from macrophages, and are alsosurface-modified to deliver duplexed siRNA to hepatocytes fordiminishing Apo B-100 protein expression, thereby inhibiting LDLproduction. Accordingly, the structures may function in two- or morecell types. Design of such structures having dual functionality mayinvolve balancing the surface coverage of siRNA (or otheroligonucleotide) so as to not, potentially, decrease the capacity forthe particle to mediate reverse cholesterol efflux and vice versa.

In one particular embodiment, structures, compositions and methodsdescribed herein are used for treating atherosclerosis. Treatingatherosclerosis may include performing a therapeutic intervention thatresults in reducing the cholesterol content of at least oneatherosclerotic plaque, or prophylactically inhibiting or preventing theformation or expansion of an atherosclerotic plaque. Generally, thevolume of the atherosclerotic plaque, and hence the degree ofobstruction of the vascular lumen, will also be reduced. In someembodiments, the structures, compositions and methods are useful fortreating atherosclerotic lesions associated with familialhyperlipidemias.

The compositions and methods described herein may reduce the cholesterolcontent of atherosclerotic plaques and/or the volume of atheroscleroticplaques. The cholesterol content may be reduced by, for example, atleast 10%-30%, at least 30%-50%, and in some instances at least 50%-85%or more. The volume of the atherosclerotic plaques may also be reduced.The reduction in plaque volume may be, for example, at least 5%-30%,often as much as 50%, and in some instances 75% or more. Methods ofdetermining the reduction of cholesterol content of atheroscleroticplaques and/or the volume of atherosclerotic plaques are known to thoseof ordinary skill in the art, and include intravascular ultrasound andmagnetic resonance imaging.

Other diseases or bodily conditions associated with abnormal lipidlevels which could benefit from the structures and/or compositionsdescribed herein include, for example, phlebosclerosis or any venouscondition in which deposits of plaques containing cholesterol or othermaterial are formed within the intima or inner media of veins, acutecoronary syndromes, angina including, stable angina, unstable angina,inflammation, sepsis, vascular inflammation, dermal inflammation,congestive heart failure, coronary heart disease (CHD), ventriculararrythmias, peripheral vascular disease, myocardial infarction, onset offatal myocardial infarction, non-fatal myocardial infarction, ischemia,cardiovascular ischemia, transient ischemic attacks, ischemia unrelatedto cardiovascular disease, ischemia-reperfusion injury, decreased needfor revascularization, coagulation disorders, thrombocytopenia, deepvein thrombosis, pancreatitis, non-alcoholic steatohepatitis, diabeticneuropathy, retinopathy, painful diabetic neuropathy, claudication,psoriasis, critical limb ischemia, impotence, dyslipidemia,hyperlipidemia, hyperlipoproteinemia, hypoalphalipoproteinemia,hypertriglyceridemia, any stenotic condition leading to ischemicpathology, obesity, diabetes including both Type I and Type II,ichtyosis, stroke, vulnerable plaques, lower-limb ulceration, severecoronary ischemia, lymphomas, cataracts, endothelial dysfunction,xanthomas, end organ dysfunction, vascular disease, vascular diseasethat results from smoking and diabetes, carotid and coronary arterydisease, regress and shrink established plaques, unstable plaques,vessel intima that is weak, unstable vessel intima, endothelial injury,endothelial damage as a result of surgical procedures, morbidityassociated with vascular disease, ulcerations in the arterial lumen,restenosis as a result of balloon angioplasty, protein storage diseases(e.g., Alzheimer's disease, prion disease), diseases of hemostasis(e.g., thrombosis, thrombophilia, disseminated intravascularcoagulation, thrombocytopenia, heparin induced thrombocytopenia,thrombotic thrombocytopenic purpura,), rheumatic diseases (e.g.,multiple sclerosis, systemic lupus erythematosis, sjogren's syndrome,polymyositis/dermatomyositis, scleroderma), neuroligical diseases (e.g.,Parkinson's disease, Alzheimer's disease), and subindications thereof.As described herein, such conditions may be treated or managed using thestructures described herein, which may optionally be adapted to regulategene expression of a target and/or to deliver nucleic acids. Certainmethods of treatment or management of such diseases or conditionsinvolve using the structures described herein to both sequestercholeresterol and function as a gene-regulating therapeutic.

Structures, compositions, and methods described herein may diagnose,prevent, treat, or manage diseases or bodily conditions associated withabnormal lipid levels, by, for example, decreasing triglycerides levels,increasing or decreasing the level of other lipids, increasing plaquestability or decreasing the probability of plaque rupture, increasing ordecreasing vasodilation, treating or preventing inflammation, treatingor preventing inflammatory diseases or an inflammatory response,strengthening or stabilizing smooth muscle and vessel intima,stimulating efflux of extracellular cholesterol for transport to theliver, modulating immune responses, mobilizing cholesterol fromatherosclerotic plaques, modifying any membrane, cell, tissue, organ,and extracellular region and/or structure in which compositional and/orfunctional modifications would be advantageous, and/or regulating genesthat express proteins that are associated with a disease or bodilycondition. Combinations of two or more such methods can also be used todiagnose, prevent, treat, or manage diseases or bodily conditions.

In another set of embodiments, the structures, compositions and methodsdescribed herein are used for treating a subject having a vascular or acardiovascular condition or is at risk of developing a cardiovascularcondition are provided. Vascular conditions are conditions that involvethe blood vessels (arteries and veins). Cardiovascular conditions areconditions that involve the heart and the blood vessels associated withthe heart. Examples of vascular conditions include diabetic retinopathy,diabetic nephropathy, renal fibrosis, hypertension, atherosclerosis,arteriosclerosis, atherosclerotic plaque, atherosclerotic plaquerupture, cerebrovascular accident (stroke), transient ischemic attack(TIA), peripheral artery disease, arterial occlusive disease, vascularaneurysm, ischemia, ischemic ulcer, heart valve stenosis, heart valveregurgitation and intermittent claudication. Examples of cardiovascularconditions include coronary artery disease, ischemic cardiomyopathy,myocardial ischemia, and ischemic or post-myocardial ischemiarevascularization.

Structures, compositions and methods described herein can also be usedfor treating a subject at risk for developing a cardiovascularcondition. The degree of risk of a cardiovascular condition depends onthe multitude and the severity or the magnitude of the risk factors thatthe subject has. Risk charts and prediction algorithms are available forassessing the risk of cardiovascular conditions in a human subject basedon the presence and severity of risk factors. One commonly usedalgorithm for assessing the risk of a cardiovascular condition in ahuman subject based on the presence and severity of risk factors is theFramingham Heart Study risk prediction score. A human subject is at anelevated risk of having a cardiovascular condition if the subject's10-year calculated Framingham Heart Study risk score is greater than10%. Another method for assessing the risk of a cardiovascular event ina human subject is a global risk score that incorporates a measurementof a level of a marker of systemic inflammation, such as CRP, into theFramingham Heart Study risk prediction score. Other methods of assessingthe risk of a cardiovascular event in a human subject include coronarycalcium scanning, cardiac magnetic resonance imaging, and/or magneticresonance angiography.

The structures, compositions and methods described herein may also beuseful for prophylactic treatments. Prophylactic treatments may beuseful following invasive vascular procedures. For instance, vascularregions having injured endothelium are at increased risk for developingatherosclerotic plaques. Therefore, invasive vascular procedures, suchas coronary angioplasty, vascular bypass grafting, and other proceduresthat injure the vascular endothelial layer, may be practiced inconjunction with the methods of the present invention. As the invasiveprocedure injures the endothelium, the structures may act to removecholesterol from the injured region and inhibit or prevent plaqueformation of expansion during endothelial healing.

Hyperlipidemias may also be treated by the compositions and methodsdescribed herein. Administration of structures, alone or bound to aprotein such as apo-A1 and apo-A2, to individuals havinghypoalphalipoproteinemia from genetic or secondary causes, familialcombined hyperlipidemia, and familial hypercholesterolemia is a usefultreatment.

In another set of embodiments, the structures described herein may beused for treating cancer. Cancer cells may be dependent upon cholesteroldelivery by HDL in order to maintain cell membrane biosynthesis andintegrity. As such, structures described herein may be adapted to mimicendogenous HDL such that they can target cancer cells. The structuresmay also function to regulate gene expression once inside the cancercells. For example, in one particular embodiment, the structures mayinclude one or more oligonucleotides adapted to reduce intracellularmiR-210 levels. Reducing intracellular miR-210 levels has been shown toinhibit angiogenesis in human umbilical vein endothelial cells, as wellas induce apoptosis in cancer cell types. In another example, structuresdescribed herein may include an oligonucleotide that selectively bindsto mRNA sequences within cancer cells to regulate gene expression. Forexample, a structure may include a nucleic acid sequence (e.g.,anti-survivin oligonucleotide) that regulates the expression ofsurviving, an anti-apoptotic protein near universally upregulated inhuman cancer. The anti-survivin oligonucleotide has the potential toselectively bind intracellular survivin mRNA, knockdown survivin proteinexpression, and induce cancer cell death. Structures described hereinmay also include other oligonucleotides to treat cancer.

In some cases, the structures may be used as contrast agents incombination with one or more other functions such as sequesteringcholesterol, delivering nucleic acids, and/or regulating geneexpression. For example, the nanostructure core of the structure maycomprise a material suitable for use as a contrast agent (e.g., gold,iron oxide, a quantum dot, radionuclide, etc.). In other embodiments,the shell may include a contrast agent. For instance, a nanoparticle orother suitable contrast agent may be embedded within the lipid bilayerof the shell, or associated with an inner or outer surface of the shell.The contrast agents may be used to enhance various imaging methods knownto those in the art such as MRI, X-ray, PET, CT, etc.

In some embodiments, structures described herein may be used asintracellular diagnostic sensors. For instance, as described herein,structures including nucleic acids associated therewith may be deliveredto the cytoplasm of cells where they regulate the expression of targetRNA sequences and their protein targets. The ability to deliver nucleicacids intact to the cell cytoplasm provides an opportunity to not onlyregulate RNA targets, but also to detect them. For instance, in someembodiments, delivery of a “molecular beacon”, where 3′ and 5′fluor-quencher pairs are in close proximity due to hairpinself-hybridization may be used to detect an intracellular target mRNAthrough complementary binding to the beacon and relief of fluorescentquenching. In other embodiments, short nucleic acids may be designed todetect the presence of intracellular proteins (e.g., aptamers) or smallmolecules (e.g., ATP-sensor) through changes in fluorescence that occurdue to target protein or small molecule binding, respectively. Thestructures described herein may be made to deliver nucleic acid sensorsfor a broad range of biomolecules that provide a convenient readout oftheir presence, for example, through increased fluorescence upon targetmolecule binding.

In some embodiments, a composition is introduced to a subject or abiological sample, and the structures of the composition and/or thesubject or biological sample are exposed to assay conditions that candetermine a disease or condition of the subject or biological sample. Atleast a portion of the structures may be retrieved from the subject orbiological sample and an assay may be performed with the structuresretrieved. The structures may be assayed for the amount and/or type ofmolecules bound to or otherwise sequestered by the structures. Forexample, in one set of embodiments, a competition assay is performed,e.g., where labeled cholesterol is added and displacement of cholesterolis monitored. The more measured uptake of labeled cholesterol, the lessbound un-labeled free cholesterol is present. This can be done, forexample, after a composition comprising the structures described hereinare administered to a subject or a biological sample, and the structuresare subsequently retrieved from the subject or biological sample. Thismethod can be used, for example, where the structures are to be used asa diagnostic agent to see how much cholesterol (unlabeled) it hassequestered in a subject or biological sample.

Other methods can also be used to determine the amount of cholesterolsequestered by structures described herein. In some cases, labeledcholesterol (e.g., fluorescently-labeled cholesterol such asNBD-cholesterol, or radioactive cholesterol) can be used. Labeledcholesterol can be added to the structures either in vitro or in vitro.By adding structures without labeled cholesterol and measuring thefluorescence increase upon binding, one can calculate the bindingconstant of labeled cholesterol to the structure. In addition, to removethe cholesterol from the structure, one can dissolve the particle (e.g.,KCN) and then measure the resultant fluorescence in solution. Comparingto standard curve can allow determination of the number of cholesterolmolecules per particle. Other methods such as organic extraction andquantitative mass spectrometry can also be used to calculate amount ofcholesterol sequestered by one or more structures described herein.

As described herein, the inventive structures may be used in“pharmaceutical compositions” or “pharmaceutically acceptable”compositions, which comprise a therapeutically effective amount of oneor more of the structures described herein, formulated together with oneor more pharmaceutically acceptable carriers, additives, and/ordiluents. The pharmaceutical compositions described herein may be usefulfor diagnosing, preventing, treating or managing a disease or bodilycondition such as those described herein, including but not limited toones associated with regulating gene expression. In some cases, thestructures and compositions can be used for both diagnosis andtherapeutic purposes. It should be understood that any suitablestructures described herein can be used in such pharmaceuticalcompositions, including those described in connection with the figures.In some cases, the structures in a pharmaceutical composition have ananostructure core comprising an inorganic material and a shellsubstantially surrounding and attached to the nanostructure core.

The pharmaceutical compositions may be specially formulated foradministration in solid or liquid form, including those adapted for thefollowing: oral administration, for example, drenches (aqueous ornon-aqueous solutions or suspensions), tablets, e.g., those targeted forbuccal, sublingual, and systemic absorption, boluses, powders, granules,pastes for application to the tongue; parenteral administration, forexample, by subcutaneous, intramuscular, intravenous or epiduralinjection as, for example, a sterile solution or suspension, orsustained-release formulation; topical application, for example, as acream, ointment, or a controlled-release patch or spray applied to theskin, lungs, or oral cavity; intravaginally or intrarectally, forexample, as a pessary, cream or foam; sublingually; ocularly;transdermally; or nasally, pulmonary and to other mucosal surfaces.

The phrase “pharmaceutically acceptable” is employed herein to refer tothose structures, materials, compositions, and/or dosage forms whichare, within the scope of sound medical judgment, suitable for use incontact with the tissues of human beings and animals without excessivetoxicity, irritation, allergic response, or other problem orcomplication, commensurate with a reasonable benefit/risk ratio.

The phrase “pharmaceutically-acceptable carrier” as used herein means apharmaceutically-acceptable material, composition or vehicle, such as aliquid or solid filler, diluent, excipient, or solvent encapsulatingmaterial, involved in carrying or transporting the subject compound fromone organ, or portion of the body, to another organ, or portion of thebody. Each carrier must be “acceptable” in the sense of being compatiblewith the other ingredients of the formulation and not injurious to thepatient. Some examples of materials which can serve aspharmaceutically-acceptable carriers include: sugars, such as lactose,glucose and sucrose; starches, such as corn starch and potato starch;cellulose, and its derivatives, such as sodium carboxymethyl cellulose,ethyl cellulose and cellulose acetate; powdered tragacanth; malt;gelatin; talc; excipients, such as cocoa butter and suppository waxes;oils, such as peanut oil, cottonseed oil, safflower oil, sesame oil,olive oil, corn oil and soybean oil; glycols, such as propylene glycol;polyols, such as glycerin, sorbitol, mannitol and polyethylene glycol;esters, such as ethyl oleate and ethyl laurate; agar; buffering agents,such as magnesium hydroxide and aluminum hydroxide; alginic acid;pyrogen-free water; isotonic saline; Ringer's solution; ethyl alcohol;pH buffered solutions; polyesters, polycarbonates and/or polyanhydrides;and other non-toxic compatible substances employed in pharmaceuticalformulations.

Wetting agents, emulsifiers and lubricants, such as sodium laurylsulfate and magnesium stearate, as well as coloring agents, releaseagents, coating agents, sweetening, flavoring and perfuming agents,preservatives and antioxidants can also be present in the compositions.

Examples of pharmaceutically-acceptable antioxidants include: watersoluble antioxidants, such as ascorbic acid, cysteine hydrochloride,sodium bisulfate, sodium metabisulfite, sodium sulfite and the like;oil-soluble antioxidants, such as ascorbyl palmitate, butylatedhydroxyanisole (BHA), butylated hydroxytoluene (BHT), lecithin, propylgallate, alpha-tocopherol, and the like; and metal chelating agents,such as citric acid, ethylenediamine tetraacetic acid (EDTA), sorbitol,tartaric acid, phosphoric acid, and the like.

The structures described herein may be orally administered, parenterallyadministered, subcutaneously administered, and/or intravenouslyadministered. In certain embodiments, a structure or pharmaceuticalpreparation is administered orally. In other embodiments, the structureor pharmaceutical preparation is administered intravenously. Alternativeroutes of administration include sublingual, intramuscular, andtransdermal administrations.

Pharmaceutical compositions described herein include those suitable fororal, nasal, topical (including buccal and sublingual), rectal, vaginaland/or parenteral administration. The formulations may conveniently bepresented in unit dosage form and may be prepared by any methods wellknown in the art of pharmacy. The amount of active ingredient which canbe combined with a carrier material to produce a single dosage form willvary depending upon the host being treated, and the particular mode ofadministration. The amount of active ingredient that can be combinedwith a carrier material to produce a single dosage form will generallybe that amount of the compound which produces a therapeutic effect.Generally, this amount will range from about 1% to about 99% of activeingredient, from about 5% to about 70%, or from about 10% to about 30%.

The inventive compositions suitable for oral administration may be inthe form of capsules, cachets, pills, tablets, lozenges (using aflavored basis, usually sucrose and acacia or tragacanth), powders,granules, or as a solution or a suspension in an aqueous or non-aqueousliquid, or as an oil-in-water or water-in-oil liquid emulsion, or as anelixir or syrup, or as pastilles (using an inert base, such as gelatinand glycerin, or sucrose and acacia) and/or as mouth washes and thelike, each containing a predetermined amount of a structure describedherein as an active ingredient. An inventive structure may also beadministered as a bolus, electuary or paste.

In solid dosage forms of the invention for oral administration(capsules, tablets, pills, dragees, powders, granules and the like), theactive ingredient is mixed with one or more pharmaceutically-acceptablecarriers, such as sodium citrate or dicalcium phosphate, and/or any ofthe following: fillers or extenders, such as starches, lactose, sucrose,glucose, mannitol, and/or silicic acid; binders, such as, for example,carboxymethylcellulose, alginates, gelatin, polyvinyl pyrrolidone,sucrose and/or acacia; humectants, such as glycerol; disintegratingagents, such as agar-agar, calcium carbonate, potato or tapioca starch,alginic acid, certain silicates, and sodium carbonate; solutionretarding agents, such as paraffin; absorption accelerators, such asquaternary ammonium compounds; wetting agents, such as, for example,cetyl alcohol, glycerol monostearate, and non-ionic surfactants;absorbents, such as kaolin and bentonite clay; lubricants, such as talc,calcium stearate, magnesium stearate, solid polyethylene glycols, sodiumlauryl sulfate, and mixtures thereof; and coloring agents. In the caseof capsules, tablets and pills, the pharmaceutical compositions may alsocomprise buffering agents. Solid compositions of a similar type may alsobe employed as fillers in soft and hard-shelled gelatin capsules usingsuch excipients as lactose or milk sugars, as well as high molecularweight polyethylene glycols and the like.

A tablet may be made by compression or molding, optionally with one ormore accessory ingredients. Compressed tablets may be prepared usingbinder (for example, gelatin or hydroxypropylmethyl cellulose),lubricant, inert diluent, preservative, disintegrant (for example,sodium starch glycolate or cross-linked sodium carboxymethyl cellulose),surface-active or dispersing agent. Molded tablets may be made in asuitable machine in which a mixture of the powdered structure ismoistened with an inert liquid diluent.

The tablets, and other solid dosage forms of the pharmaceuticalcompositions of the present invention, such as dragees, capsules, pillsand granules, may optionally be scored or prepared with coatings andshells, such as enteric coatings and other coatings well known in thepharmaceutical-formulating art. They may also be formulated so as toprovide slow or controlled release of the active ingredient thereinusing, for example, hydroxypropylmethyl cellulose in varying proportionsto provide the desired release profile, other polymer matrices,liposomes and/or microspheres. They may be formulated for rapid release,e.g., freeze-dried. They may be sterilized by, for example, filtrationthrough a bacteria-retaining filter, or by incorporating sterilizingagents in the form of sterile solid compositions that can be dissolvedin sterile water, or some other sterile injectable medium immediatelybefore use. These compositions may also optionally contain opacifyingagents and may be of a composition that they release the activeingredient(s) only, or in a certain portion of the gastrointestinaltract, optionally, in a delayed manner. Examples of embeddingcompositions that can be used include polymeric substances and waxes.The active ingredient can also be in micro-encapsulated form, ifappropriate, with one or more of the above-described excipients.

Liquid dosage forms for oral administration of the structures describedherein include pharmaceutically acceptable emulsions, microemulsions,solutions, dispersions, suspensions, syrups and elixirs. In addition tothe inventive structures, the liquid dosage forms may contain inertdiluents commonly used in the art, such as, for example, water or othersolvents, solubilizing agents and emulsifiers, such as ethyl alcohol,isopropyl alcohol, ethyl carbonate, ethyl acetate, benzyl alcohol,benzyl benzoate, propylene glycol, 1,3-butylene glycol, oils (inparticular, cottonseed, groundnut, corn, germ, olive, castor and sesameoils), glycerol, tetrahydrofuryl alcohol, polyethylene glycols and fattyacid esters of sorbitan, and mixtures thereof.

Besides inert diluents, the oral compositions can also include adjuvantssuch as wetting agents, emulsifying and suspending agents, sweetening,flavoring, coloring, perfuming and preservative agents.

Suspensions, in addition to the active compounds, may contain suspendingagents as, for example, ethoxylated isostearyl alcohols, polyoxyethylenesorbitol and sorbitan esters, microcrystalline cellulose, aluminummetahydroxide, bentonite, agar-agar and tragacanth, and mixturesthereof.

Formulations of the pharmaceutical compositions described herein (e.g.,for rectal or vaginal administration) may be presented as a suppository,which may be prepared by mixing one or more compounds of the inventionwith one or more suitable nonirritating excipients or carrierscomprising, for example, cocoa butter, polyethylene glycol, asuppository wax or a salicylate, and which is solid at room temperature,but liquid at body temperature and, therefore, will melt in the body andrelease the structures.

Dosage forms for the topical or transdermal administration of astructure described herein include powders, sprays, ointments, pastes,foams, creams, lotions, gels, solutions, patches and inhalants. Theactive compound may be mixed under sterile conditions with apharmaceutically-acceptable carrier, and with any preservatives,buffers, or propellants which may be required.

The ointments, pastes, creams and gels may contain, in addition to theinventive structures, excipients, such as animal and vegetable fats,oils, waxes, paraffins, starch, tragacanth, cellulose derivatives,polyethylene glycols, silicones, bentonites, silicic acid, talc and zincoxide, or mixtures thereof.

Powders and sprays can contain, in addition to the structures describedherein, excipients such as lactose, talc, silicic acid, aluminumhydroxide, calcium silicates and polyamide powder, or mixtures of thesesubstances. Sprays can additionally contain customary propellants, suchas chlorofluorohydrocarbons and volatile unsubstituted hydrocarbons,such as butane and propane.

Transdermal patches have the added advantage of providing controlleddelivery of a structure described herein to the body. Dissolving ordispersing the structure in the proper medium can make such dosageforms. Absorption enhancers can also be used to increase the flux of thestructure across the skin. Either providing a rate controlling membraneor dispersing the structure in a polymer matrix or gel can control therate of such flux.

Ophthalmic formulations, eye ointments, powders, solutions and the like,are also contemplated as being within the scope of this invention.

Pharmaceutical compositions described herein suitable for parenteraladministration comprise one or more inventive structures in combinationwith one or more pharmaceutically-acceptable sterile isotonic aqueous ornonaqueous solutions, dispersions, suspensions or emulsions, or sterilepowders which may be reconstituted into sterile injectable solutions ordispersions just prior to use, which may contain sugars, alcohols,antioxidants, buffers, bacteriostats, solutes which render theformulation isotonic with the blood of the intended recipient orsuspending or thickening agents.

Examples of suitable aqueous and nonaqueous carriers, which may beemployed in the pharmaceutical compositions described herein includewater, ethanol, polyols (such as glycerol, propylene glycol,polyethylene glycol, and the like), and suitable mixtures thereof,vegetable oils, such as olive oil, and injectable organic esters, suchas ethyl oleate. Proper fluidity can be maintained, for example, by theuse of coating materials, such as lecithin, by the maintenance of therequired particle size in the case of dispersions, and by the use ofsurfactants.

These compositions may also contain adjuvants such as preservatives,wetting agents, emulsifying agents and dispersing agents. Prevention ofthe action of microorganisms upon the inventive structures may befacilitated by the inclusion of various antibacterial and antifungalagents, for example, paraben, chlorobutanol, phenol sorbic acid, and thelike. It may also be desirable to include isotonic agents, such assugars, sodium chloride, and the like into the compositions. Inaddition, prolonged absorption of the injectable pharmaceutical form maybe brought about by the inclusion of agents which delay absorption suchas aluminum monostearate and gelatin.

Delivery systems suitable for use with structures and compositionsdescribed herein include time-release, delayed release, sustainedrelease, or controlled release delivery systems, as described herein.Such systems may avoid repeated administrations of the structures inmany cases, increasing convenience to the subject and the physician.Many types of release delivery systems are available and known to thoseof ordinary skill in the art. They include, for example, polymer basedsystems such as polylactic and/or polyglycolic acid, polyanhydrides, andpolycaprolactone; nonpolymer systems that are lipid-based includingsterols such as cholesterol, cholesterol esters, and fatty acids orneutral fats such as mono-, di- and triglycerides; hydrogel releasesystems; silastic systems; peptide based systems; wax coatings;compressed tablets using conventional binders and excipients; orpartially fused implants. Specific examples include, but are not limitedto, erosional systems in which the composition is contained in a formwithin a matrix, or diffusional systems in which an active componentcontrols the release rate. The compositions may be as, for example,microspheres, hydrogels, polymeric reservoirs, cholesterol matrices, orpolymeric systems. In some embodiments, the system may allow sustainedor controlled release of the active compound to occur, for example,through control of the diffusion or erosion/degradation rate of theformulation. In addition, a pump-based hardware delivery system may beused in some embodiments. The structures and compositions describedherein can also be combined (e.g., contained) with delivery devices suchas syringes, pads, patches, tubes, films, MEMS-based devices, andimplantable devices.

Use of a long-term release implant may be particularly suitable in somecases. “Long-term release,” as used herein, means that the implant isconstructed and arranged to deliver therapeutic levels of thecomposition for at least about 30 or about 45 days, for at least about60 or about 90 days, or even longer in some cases. Long-term releaseimplants are well known to those of ordinary skill in the art, andinclude some of the release systems described above.

Injectable depot forms can be made by forming microencapsule matrices ofthe structures described herein in biodegradable polymers such aspolylactide-polyglycolide. Depending on the ratio of structure topolymer, and the nature of the particular polymer employed, the rate ofrelease of the structure can be controlled. Examples of otherbiodegradable polymers include poly(orthoesters) and poly(anhydrides).

When the structures described herein are administered aspharmaceuticals, to humans and animals, they can be given per se or as apharmaceutical composition containing, for example, about 0.1% to about99.5%, about 0.5% to about 90%, or the like, of structures incombination with a pharmaceutically acceptable carrier.

The administration may be localized (e.g., to a particular region,physiological system, tissue, organ, or cell type) or systemic,depending on the condition to be treated. For example, the compositionmay be administered through parental injection, implantation, orally,vaginally, rectally, buccally, pulmonary, topically, nasally,transdermally, surgical administration, or any other method ofadministration where access to the target by the composition isachieved. Examples of parental modalities that can be used with theinvention include intravenous, intradermal, subcutaneous, intracavity,intramuscular, intraperitoneal, epidural, or intrathecal. Examples ofimplantation modalities include any implantable or injectable drugdelivery system. Oral administration may be useful for some treatmentsbecause of the convenience to the patient as well as the dosingschedule.

Regardless of the route of administration selected, the structuresdescribed herein, which may be used in a suitable hydrated form, and/orthe inventive pharmaceutical compositions, are formulated intopharmaceutically-acceptable dosage forms by conventional methods knownto those of skill in the art.

The compositions described herein may be given in dosages, e.g., at themaximum amount while avoiding or minimizing any potentially detrimentalside effects. The compositions can be administered in effective amounts,alone or in a combinations with other compounds. For example, whentreating cancer, a composition may include the structures describedherein and a cocktail of other compounds that can be used to treatcancer.

The phrase “therapeutically effective amount” as used herein means thatamount of a material or composition comprising an inventive structurewhich is effective for producing some desired therapeutic effect in asubject at a reasonable benefit/risk ratio applicable to any medicaltreatment. Accordingly, a therapeutically effective amount may, forexample, prevent, minimize, or reverse disease progression associatedwith a disease or bodily condition. Disease progression can be monitoredby clinical observations, laboratory and imaging investigations apparentto a person skilled in the art. A therapeutically effective amount canbe an amount that is effective in a single dose or an amount that iseffective as part of a multi-dose therapy, for example an amount that isadministered in two or more doses or an amount that is administeredchronically.

The effective amount of any one or more structures described herein maybe from about 10 ng/kg of body weight to about 1000 mg/kg of bodyweight, and the frequency of administration may range from once a day toonce a month. However, other dosage amounts and frequencies also may beused as the invention is not limited in this respect. A subject may beadministered one or more structure described herein in an amounteffective to treat one or more diseases or bodily conditions describedherein.

An effective amount may depend on the particular condition to betreated. One of ordinary skill in the art can determine what aneffective amount of the composition is by, for example, methods such asassessing liver function tests (e.g. transaminases), kidney functiontests (e.g. creatinine), heart function tests (e.g. troponin, CRP),immune function tests (e.g. cytokines like IL-1 and TNF-alpha), etc. Theeffective amounts will depend, of course, on factors such as theseverity of the condition being treated; individual patient parametersincluding age, physical condition, size and weight; concurrenttreatments; the frequency of treatment; or the mode of administration.These factors are well known to those of ordinary skill in the art andcan be addressed with no more than routine experimentation. In somecases, a maximum dose be used, that is, the highest safe dose accordingto sound medical judgment.

Actual dosage levels of the active ingredients in the pharmaceuticalcompositions described herein may be varied so as to obtain an amount ofthe active ingredient that is effective to achieve the desiredtherapeutic response for a particular patient, composition, and mode ofadministration, without being toxic to the patient.

The selected dosage level will depend upon a variety of factorsincluding the activity of the particular inventive structure employed,the route of administration, the time of administration, the rate ofexcretion or metabolism of the particular structure being employed, theduration of the treatment, other drugs, compounds and/or materials usedin combination with the particular structure employed, the age, sex,weight, condition, general health and prior medical history of thepatient being treated, and like factors well known in the medical arts.

A physician or veterinarian having ordinary skill in the art can readilydetermine and prescribe the effective amount of the pharmaceuticalcomposition required. For example, the physician or veterinarian couldstart doses of the structures described herein employed in thepharmaceutical composition at levels lower than that required to achievethe desired therapeutic effect and then gradually increasing the dosageuntil the desired effect is achieved.

In some embodiments, a structure or pharmaceutical composition describedherein is provided to a subject chronically. Chronic treatments includeany form of repeated administration for an extended period of time, suchas repeated administrations for one or more months, between a month anda year, one or more years, or longer. In many embodiments, a chronictreatment involves administering a structure or pharmaceuticalcomposition repeatedly over the life of the subject. For example,chronic treatments may involve regular administrations, for example oneor more times a day, one or more times a week, or one or more times amonth. In general, a suitable dose such as a daily dose of a structuredescribed herein will be that amount of the structure that is the lowestdose effective to produce a therapeutic effect. Such an effective dosewill generally depend upon the factors described above. Generally dosesof the structures described herein for a patient, when used for theindicated effects, will range from about 0.0001 to about 100 mg per kgof body weight per day. The daily dosage may range from 0.001 to 50 mgof compound per kg of body weight, or from 0.01 to about 10 mg ofcompound per kg of body weight. However, lower or higher doses can beused. In some embodiments, the dose administered to a subject may bemodified as the physiology of the subject changes due to age, diseaseprogression, weight, or other factors.

If desired, the effective daily dose of the active compound may beadministered as two, three, four, five, six or more sub-dosesadministered separately at appropriate intervals throughout the day,optionally, in unit dosage forms. For example, instructions and methodsmay include dosing regimens wherein specific doses of compositions,especially those including structures described herein having aparticular size range, are administered at specific time intervals andspecific doses to achieve reduction of cholesterol (or other lipids)and/or treatment of disease while reducing or avoiding adverse effectsor unwanted effects.

While it is possible for a structure described herein to be administeredalone, it may be administered as a pharmaceutical composition asdescribed above. The present invention also provides any of theabove-mentioned compositions useful for diagnosing, preventing,treating, or managing a disease or bodily condition packaged in kits,optionally including instructions for use of the composition. That is,the kit can include a description of use of the composition forparticipation in the disease or bodily condition. The kits can furtherinclude a description of use of the compositions as discussed herein.The kit also can include instructions for use of a combination of two ormore compositions described herein. Instructions also may be providedfor administering the composition by any suitable technique, such asorally, intravenously, or via another known route of drug delivery.

The kits described herein may also contain one or more containers, whichcan contain components such as the structures, signaling entities,and/or biomolecules as described. The kits also may contain instructionsfor mixing, diluting, and/or administrating the compounds. The kits alsocan include other containers with one or more solvents, surfactants,preservatives, and/or diluents (e.g., normal saline (0.9% NaCl), or 5%dextrose) as well as containers for mixing, diluting or administeringthe components to the sample or to the patient in need of suchtreatment.

The compositions of the kit may be provided as any suitable form, forexample, as liquid solutions or as dried powders. When the compositionprovided is a dry powder, the powder may be reconstituted by theaddition of a suitable solvent, which may also be provided. Inembodiments where liquid forms of the composition are used, the liquidform may be concentrated or ready to use. The solvent will depend on theparticular inventive structure and the mode of use or administration.Suitable solvents for compositions are well known and are available inthe literature.

The kit, in one set of embodiments, may comprise one or more containerssuch as vials, tubes, and the like, each of the containers comprisingone of the separate elements to be used in the method. For example, oneof the containers may comprise a positive control in the assay.Additionally, the kit may include containers for other components, forexample, buffers useful in the assay.

As used herein, a “subject” or a “patient” refers to any mammal (e.g., ahuman). Examples of subjects or patients include a human, a non-humanprimate, a cow, a horse, a pig, a sheep, a goat, a dog, a cat or arodent such as a mouse, a rat, a hamster, or a guinea pig. Generally,the invention is directed toward use with humans. A subject may be asubject diagnosed with a certain disease or bodily condition orotherwise known to have a disease or bodily condition. In someembodiments, a subject may be diagnosed as, or known to be, at risk ofdeveloping a disease or bodily condition. In some embodiments, a subjectmay be diagnosed with, or otherwise known to have, a disease or bodilycondition associated with abnormal lipid levels, as described herein. Incertain embodiments, a subject may be selected for treatment on thebasis of a known disease or bodily condition in the subject. In someembodiments, a subject may be selected for treatment on the basis of asuspected disease or bodily condition in the subject. In someembodiments, the composition may be administered to prevent thedevelopment of a disease or bodily condition. However, in someembodiments, the presence of an existing disease or bodily condition maybe suspected, but not yet identified, and a composition of the inventionmay be administered to diagnose or prevent further development of thedisease or bodily condition.

A “biological sample,” as used herein, is any cell, body tissue, or bodyfluid sample obtained from a subject. Non-limiting examples of bodyfluids include, for example, lymph, saliva, blood, urine, and the like.Samples of tissue and/or cells for use in the various methods describedherein can be obtained through standard methods including, but notlimited to, tissue biopsy, including punch biopsy and cell scraping,needle biopsy; or collection of blood or other bodily fluids byaspiration or other suitable methods.

The following examples are intended to illustrate certain embodiments ofthe present invention, but are not to be construed as limiting and donot exemplify the full scope of the invention.

EXAMPLES Example 1

This example describes methods for chemically tailoring the surface ofhybrid structures in the form of DNA-HDL AuNPs so as to control theratio of surface components. The DNA-HDL AuNPs may function to bothsequester cholesterol and deliver nucleic acids or regulate geneexpression.

Five nm diameter citrate-stabilized Au NPs (Ted Pella) were used totemplate spherical synthetic HDL AuNPs using two synthetic approaches(FIGS. 2A and 2B).

HDL AuNPs were fabricated in solutions of H₂O/ethanol (EtOH). AuNPs,DNA, APOAI, and each of the phospholipids are soluble and stable inH₂O/EtOH (up to 50% EtOH). This method allows for individual surfacecomponents to be added step-wise to the HDL AuNPs, and the removal ofunreacted components and EtOH.

In a typical HDL AuNP synthesis, citrate-stabilized gold nanoparticles(80 nM, 5±0.75 nm, Ted Pella, Inc.) in aqueous solution are mixed with5-fold excess of purified human APOA1 (400 nM, Biodesign International)in a glass vial. This solution is allowed to mix overnight at roomtemperature while stirring. Next, a 1:1 ratio of1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine-N-[3-(2-pyridyldithio)propionate]:1-2-dipalmitoyl-sn-glycero-3-phosphocholine (Avanti Polar Lipids) eachin 100-fold excess with respect to the concentration of AuNPs wasprepared in chloroform. The phospholipid mixture is then added to theaqueous AuNP/APOA1 solution which results in a layered mixture. Themixture is vortexed and briefly sonicated which results in a pink andfrothy mixture. The mixture is gradually heated to ˜65° C. in order toevaporate the chloroform. After allowing the solution to cool,purification of the HDL-AuNPs is accomplished via centrifugation (15,800g×45 min) and re-suspension in Nanopure™ water.

In the case of the first synthetic method (FIG. 2A), HDL AuNPs werefabricated as described above and increasing concentrations of5′-cholesterylated DNA (chol-DNA) were added to the HDL AuNPs. Forexample, chol-DNA-HDL AuNPs were fabricated by adding a 100-fold molarexcess of cholesteryl-DNA to the HDL AuNPs. All oligonucleotides werefabricated using standard phosphoramidite chemistry (Expedite 8909) andpurified using reverse phase HPLC (Varian ProStar 210). The sequencesused are shown in Table 1. Following a 4-hour incubation, DNA-HDL AuNPswere distributed into 1 mL aliquots and centrifuged (15,800 g×45 min) toremove DNA not bound to the HDL AuNP surface, the supernatant decanted,and then the DNA-HDL AuNPs were re-suspended in ˜30 μL of phosphatebuffered saline (1×PBS, 0.15M NaCl, 0.01M phosphate buffer, pH=7.5). Thealiquots were vortexed and briefly sonicated to ensure full suspensionof the chol-DNA-HDL AuNP pellet. Concentrated solutions of chol-DNA-HDLAuNPs were combined to yield a final concentration of ˜1 μM. Particleconcentrations were measured using a UV-Vis spectrophotometer (Agilent8453). The λ_(max)=520 nm for 5 nm AuNPs and the extinctionco-efficient, e=9.696×10⁶ M⁻¹ cm⁻¹. Particles were stored at 4° C. untiluse.

3′-fluorophore labeled (e.g. Cyanine 3 or 5) DNA was used to quantifythe amount of DNA bound to the HDL AuNP surface. Also, using thefluorescently labeled DNA, a binding isotherm was constructed tocalculate the K_(d) for cholesterol-DNA to the surface of the HDL AuNPs.

For the second synthetic method (FIG. 2B), synthesis was initiated inH₂O where 5 nm AuNPs were first surface functionalized with APOAI. APOAIadsorbs to the surface of the AuNPs; however, when adding alkyl-thiololigos, which bind tightly to the AuNP surface, ligand exchange maydrive APOAI off the surface. To some degree, surface adsorption of APOAIand thiol-modified DNA can be controlled by stoichiometry. In the eventthat thiol-DNA loading is compromised by rapid APOAI release, primaryamines on APOAI can be modified to thiol groups using Traut's reagent,which may ensure APOAI attachment while not impairing function. Traut'smodification of APOAI has been used for HDL AuNPs with no appreciablydifferences noted in cholesterol efflux assays when compared to HDLAuNPs and natural APOAI (data not shown). The NaCl concentration wasincreased to near physiologic (0.15 M, slowly increasing so as not toirreversibly de-stabilize the colloid), whereupon thiol-DNA(antago-miR-210/control) was added in increasing stoichiometric amountswith reference to the AuNPs. Finally, PLs were added in ethanolicsolution to functionalize remaining sites on the developing DNA-HDL AuNPsurface. Final constructs were purified using centrifugation. In somecases, centrifugation may promote irreversible nanoparticle aggregationin which case either dialysis or a combination of filtration/dialysis(diafiltration) can be used for purification.

TABLE 1 Sequence Name Sequence chol-antago-miR-2105′-Cholesteryl-TEG-(A)₁₀- TCA GCC GCT GTC ACA CGC ACA G-3′chol-antago-miR-210-  5′-Cholesteryl-TEG-(A)₁₀- Fluor (F)TCA GCC GCT GTC ACA CGC ACA G-3′ chol-control-antago-miR5′-Cholesteryl-TEG-(A)₁₀- CCC CGT AAT CTT CAT AAT CCG AG-3′chol-control-antago-miR- 5′-Cholesteryl-TEG-(A)₁₀- Fluor (F)GCC TTA CGC TrAC CCG GAG ACC A-3′

Example 2

This examples shows that structures in the form of DNA-HDL AuNPs havelow toxicity and can be used to regulate gene expression in cells. TheDNA was electrostatically physisorbed onto a phospholipid bilayer shellof the structures.

HDL AuNPs were fabricated using the method described in Example 1 inconnection with FIG. 2A, and then mixed with DNA antago-miRs terminallymodified with cholesterol. The resultant DNA-HDL AuNPs were centrifuged(×3) for purification away from unbound cholesterol-labeled DNA. Theadded DNAs are reverse complement “antago-miR” molecules of targetedmicroRNA-210. MicroRNA-210 is the pathognomic hypoxia regulatedmicroRNA. Reducing intracellular miR-210 levels has been shown toinhibit angiogenesis in human umbilical vein endothelial cells (HUVECs),as well as induce apoptosis in cancer cell types. As HDL AuNPs naturallytarget endothelial cells, HUVECs were used for these experiments.Cellular hypoxia was chemically induced using cobalt chloride (CoCl₂), awell established mechanism for promoting HIF-1α driven expression fromhypoxia response elements where miR-210 is a well-known product. DNA-HDLAuNP treatment did not cause cell toxicity as measured with a lactatedehydrogenase (LDH) assay (FIG. 5). Measured with RT-PCR following totalRNA extraction from treated versus untreated cells, antago-miR-210-HDLAuNPs function to target miR-210, versus scrambled controls, andsignificantly reduce HUVEC miR-210 levels (FIG. 6).

Example 3

This example shows a comparison between the use of hybrid DNA-HDL-AuNPstructures and DNA-AuNP structures for intracellular nucleic acidregulation.

DNA-HDL AuNPs were fabricated with either DNA antagomiR-210oligonucleotides (5-tcagccgctgtgacacgcacag-a₍₁₀₎-SH-3) or control DNAoligonucleotides (5-ccccgtaatcttcataatccgag-a₍₁₀₎-SH-3). The controloligonucleotides do not have sequence complementarity to known expressedhuman RNA sequences. MiR-210 has been shown to be upregulated underhypoxic cellular conditions where it functions to regulate and calibratethe global cellular response to normoxia-hypoxia. HUVECs were studiedwhich were chemically induced to a hypoxic state by using cobaltchloride (CoCl₂, 300 micromolar). Under these conditions, miR-210 levelswere highly increased. Either 13 nm gold nanoparticles (AuNPs) surfacefunctionalized with the DNA reverse complement of miR-210, known asantago-miR-210 (sequence above) according to standard procedures (Rosiet al, Science, 2006, 312, p. 1027), or HDL AuNPs co-loaded withantago-miR-210 sequences (sequence above) were fabricated. In the caseof the antago-miR-210-HDL AuNPs, the DNA antago-miR-210 sequences wereelectrostatically physisorbed to the surface of the HDL AuNPs. In eachcase, the final conjugates were purified using repeated centrifugationand re-suspension in 1× phosphate buffered saline (3×, 15,000 RPM).Control DNA antago-miR was fabricated and loaded to the goldnanoparticle conjugates in a similar fashion (sequence above).

The first observation that is strikingly significant with regard to thesuccessful cytoplasmic delivery of targeted therapeutic nucleic acids byusing a hybrid DNA-HDL AuNP structure, is the direct observation that asignificant number of 5 nm DNA-HDL AuNPs reside in the cytoplasmiccompartment of cells. FIGS. 7A-7C are electron micrographs (EM) of amurine macrophage (J774) grown in monolayer cell culture after exposureto the DNA-HDL AuNP structures (24 hour transfection, 50 nM HDL AuNPs).The EM demonstrates 5 nm DNA-HDL AuNP structures that are free withinthe cytoplasmic compartment (FIGS. 7A-7B). Numerous collections ofDNA-HDL AuNPs are seen in the cytoplasmic compartment of the cell (seearrow in FIG. 7A). Magnification of the arrow is shown in FIG. 7B, whichdemonstrates a collection of structures within (A) and outside of (B)cytoplasmic vesicles. A magnified image (FIG. 7C) of the areas indicatedin A, B in FIG. 7B clearly demonstrate the structures (5 nm diameter).One can contrast a group of DNA-AuNP structures that are within anintracellular vesicle (A), versus DNA-HDL AuNP structures that are freein the cytoplasm (B). This observation led to the hypothesis thatcertain structures can be used successfully for regulating intracellularRNA species (e.g., endogenous microRNA (miR) or messenger RNA (mRNA)),such as HDL AuNP structures that also include a targeted nucleic acid(DNA or RNA) therapeutic (e.g. antago-miR, siRNA, miR, etc).

The ability of different structures to downregulate intracellularmiR-210 levels upon transfection to the cells under CoCl₂ induction ofmiR-210 was compared. miR-210 levels were first normalized againstendogenous GAPDH, and then versus miR-210 in the HUVEC cells inducedwith CoCl₂, but not treated with AuNPs. As shown in FIG. 8A, CoCl₂effectively increases miR-210 expression in HUVEC cells versus those notexposed to CoCl₂. Cells exposed to antago-miR-210 HDL AuNPs (APOA1, 50nM) demonstrate a significant knockdown of miR-210 levels at 24, 48, and72 hours. At 72 hours, it appeared that the cells are beginning torecover. The antago-miR-control HDL AuNPs demonstrate no decrease inmiR-210 expression. As a means of comparison, 13 nm AuNPs fabricatedwith surface-bound antagomiR-210 and control sequences. Transfection ofthese structures (1 nM) resulted in modest knockdown of miR-210, whilethe control demonstrated limited knockdown, as expected. Taken together,these data demonstrate that nucleic acids, in this case DNA antagomiRsto miR-210, carried in the context of the HDL AuNPs (surface physisorbedin this case) can effectively target and regulate intracellular nucleicacid species (e.g., miR-210). The control particles show minimaloff-target, non-specific activity in the context of miR-210 expression.

Data also demonstrates that transfection of antago-miR-210-HDL AuNPs arenon-toxic. This was determined by assaying the cellular release oflactate dehydrogenase (LDH), a marker of plasma membrane disruption. Inthe case of loss of cellular plasma membrane integrity, the cytoplasmicenzyme lactate dehydrogenase (LDH) leaked into the cell culture medium.Using a colorimetric assay for LDH, differences between HUVEC cellstreated with antago-miR-210 AuNPs (13 nm diameter), previouslydemonstrated to be non-toxic to cultured cells (Massich, et al, MolPharm, 6(6), p. 1934, 2009), and antago-miR-210/control HDL-AuNPs wereassessed. FIG. 8B shows LDH toxicity toward HUVEC cells. The maximumpossibile LDH activity (lysed cells) is demonstrated on the far right.As shown, CoCl₂ induced and non-induced cells show little LDH leak intothe media consistent with minimal plasma-membrane disruption atbaseline. Cells treated with either antago-miR-210/control AuNPs (13 nm,1 nM) or the antago-miR-210/control HDL AuNPs (5 nm, 50 nM) demonstrateno increase in cell toxicity over baseline.

Furthermore, it was demonstrated (FIG. 8C), that a second set ofstructures effectively targeted and downregulated miR-210 in HUVECcells. These structures were fabricated similarly to those above,however, they have covalently coupled (vs. adsorbed) DNA antago-miRs tomiR-210 or control oligos. As shown in FIG. 8C, miR-210 regulation isefficiently achieved using structures with or without phospholipids(PLs), that target miR-210 (a210) in HUVEC cells. In all cases, a 5 nmAuNP serves as the templating nanostructure core material, and in allcases Apolipoprotein A-I (APOAI) is present on the surface of theconstructs.

Specifically, FIG. 8C shows miR-210 knockdown in HUVECs using structureswhere the antagomiR to microRNA-210 is end-modified with a thiol foradsorption to the surface of the 5 nm AuNP at the core of the HDL AuNP.As shown, the positive control (HUVEC-induced) HUVEC cells induced withCoCl₂ demonstrate strong miR-210 expression as compared to theHUVEC-uninduced. Two sets of particles were fabricated and transfectedinto CoCl₂ induced HUVEC cells. The first two bars demonstrate 5 nmAuNPs with APOAI protein and bound antagomiR-DNA to miR-210 (5-APO-a210)versus the same construct but with non-targeted control DNA(5-APO-c210). In the case of the targeted agent, miR-210 is reducedapproximately 60%. Bars 3 and 4 represent another set of constructs,similar to the first two, however each also contain the phospholipidbilayer used for the standards HDL AuNPs. As shown, 5-APO-a210-PLs,targeted to knockdown miR-210, do so to the tune of about 60%. Thecontrol particles (5-APO-c210-PLs) do not demonstrate miR-210 knockdown.

Overall, these data show cytoplasmic localization of HDL AuNPs,effective delivery of antago-miR-210 for regulating intracellularmiR-210 expression by the antago-miR-210 HDL AuNPs, and lack of toxicityof the antago-miR-210 HDL AuNPs.

Example 4

This example shows the use of structures such as hybrid chol-DNA-HDLAuNPs as cellular delivery vehicles for nucleic acids.

High density lipoproteins avidly target cancer cells which over-expressHDL receptors. The general need for cholesterol uptake by cancer cellshas stimulated interest in using recombinant lipoproteins, especiallyrecombinant HDL, engineered for targeted therapeutic delivery. Advancedprostate cancer cells that proliferate in vivo despite systemic androgenablation appear androgen insensitive; however, data demonstrate theyacquire the capacity to uptake cholesterol from HDL and endogenouslyproduce testosterone to maintain growth. Thus, prostate cancerrepresents a unique case where the dual need for cholesterol for bothmembrane integrity and testosterone production provides an ideal modelin which to test gene delivery strategies leveraging an HDL biomimetic.

HDL AuNPs tightly bind the fluorescent cholesterol analogue,25-[N-[(7-nitro-2-1,3-benzoxadiazol-4-yl)methyl]amino]-27-norcholesterol(NBD-cholesterol) (K_(d)=3.8 nM). HDL AuNPs may have ˜3 copies ofapolipoprotein A-I (APOAI) on their surface and have an outer leafletmonolayer of zwitterionic dipalmitoyl-phosphatidylcholine (DPPC). Due tothe tight binding of NBD-cholesterol by biomimetic HDL AuNPs, the knownelectrostatic complexation of nucleic acids with phosphocholinecontaining phospholipids, and data supporting spontaneous associationand effective cellular delivery of cholesterylated nucleic acids bynatural HDL species, we hypothesized that hybrid HDL AuNPs with adsorbedcholesteryl-DNA species (chol-DNA-HDL AuNPs) could be synthesized denovo for cellular nucleic acid delivery.

Biomimetic HDL nanostructures that closely mimics the size, shape, andsurface chemistry of naturally occurring mature spherical HDL werefabricated with surface-immobilized cholesteryl-conjugated DNA sequencesusing the method described in Example 1 and according to the steps shownin FIG. 3. Briefly, an aqueous solution of colloidal gold nanoparticles(AuNPs, 5+/−0.15 nm) was mixed with apolipoprotein A-I (APOAI). Amixture of phospholipids was then added to the surface of the AuNPs toform biomimetic HDL AuNPs. The HDL AuNPs are purified by centrifugationand re-suspension in water. The cholesterylated reverse complement DNA“antagomiR” to microRNA-210 (miR-210) and control scrambled DNA werechosen for this experiment. The HDL AuNPs described above were incubatedwith cholesteryl-DNA oligos (100:1, chol-DNA:AuNPs) in Nanopure™ water.Following a 4-hour incubation, chol-DNA-HDL AuNPs were pelleted (15,800g, 45 min), and re-suspended in phosphate buffered saline (1×PBS, 0.15MNaCl, 0.01M phosphate buffer, pH=7.5) to remove nucleic acids not boundto the HDL AuNP surface. FIG. 3 shows transmission electron micrographsof an individual 5 nm AuNP and chol-DNA-HDL AuNP.

Dynamic light scattering was used to assess the size increase of thestructures at each step of the synthetic process. As expected, thehydrodynamic diameter of the structures increased upon APOAI addition(9±1 nm), HDL AuNP formation (10±1 nm), and cholesterylated nucleic acidaddition (1±1 nm) (Table 2). UV-Vis spectroscopy confirms the stabilityof the DNA-HDL AuNP structures in buffered saline. A surface plasmonband centered at ˜520 nm, consistent with disperse rather thanaggregated AuNPs, (ref this) demonstrates conjugate stability followingsurface functionalization (Table 2). Furthermore, for the chol-DNA-HDLAuNPs, a strong absorption band at 260 nm which is consistent with DNAon the conjugate surface.

TABLE 2 APOAI- HDL Chol-DNA-HDL AuNP AuNP AuNP AuNP Size (nm) 6 ± 2 9 ±1 10 ± 1  11 ± 1 UV-Vis λmax (nm) 523 522 524 524 APOAI:AuNP N/A 3 ± 0 2± 0  2 ± 1 Molar ratio Chol-DNA:AuNP N/A N/A N/A 13 ± 1 Molar ratio

The number of oligonucleotides on the surface of chol-DNA-HDL AuNPs wasquantified using fluorescently labeled oligonucleotides and found to be˜13 per structure. Finally, fluorophore-labeled apolipoprotein A-I(APOAI) was used to fabricate HDL AuNPs and chol-DNA-HDL AuNPs in orderto quantify the number of APOAI molecules bound to the surface. Datademonstrate that there were ˜2 copies of APOAI on the surface of thechol-DNA HDL AuNPs and that APOAI remained bound to the structuresurface in the presence of chol-DNA.

Translation of mRNA is a cytoplasmic process heavily regulated byendogenous microRNAs (miRs). Effective regulation of cytoplasmic RNAswith short nucleic acids requires avoidance of endosomal sequestration.The cellular uptake of chol-DNA-HDL AuNPs, sub-cellular localization,and an assessment of cellular cytotoxicity was performed as describedabove. By using chol-DNA-HDL AuNPs with fluorophore labeledoligonucleotides, confocal fluorescent light microscopy revealed thatthe constructs associate with and rapidly enter PC3 cells (FIGS. 9A-9D).

FIGS. 9A-9D are fluorescent confocal microscopy images and FIGS. 9E-9Hare transmission electron microscopy images showing cellulardistribution of chol-DNA-HDL AuNPs in PC3 cells. For both confocal andTEM experiments, chemical hypoxia was induced in PC3 cells with 300 μMcobalt chloride (CoCl₂) for 12 hours prior to chol-DNA-HDL AuNPtreatment (50 nM, final). Left. Chol-DNA-HDL AuNPs fabricated withfluor-labelled DNA (“AuNP”) were incubated with cells and imaged atvarious time points. Keratin and nuclei (“Hoescht”) were stained aftercellular fixation. Images were taken after 4 (FIG. 9A), 8 (FIG. 9B), 12(FIG. 9C), and 24 (FIG. 9D) hour incubations with chol-DNA-HDL AuNPs.For electron microscopy images were obtained after 16 hour chol-DNA-HDLAuNP transfection. Arrows indicate AuNPs in the cytoplasm of the PC3cell. Magnifications: (FIG. 9E) 890×, (FIG. 9F) 2900×, (FIG. 9G) 6800×,(FIG. 9H) 98000×.

At ˜4 hours, the fluorescent signal was localized to the cell membrane,and subsequently internalized into punctuate vesicles. The fluorescentsignal then appears to distribute homogeneously within the cellcytoplasm prior to being repackaged in vesicles at ˜24 hours. These datasupport that fluor-labeled chol-DNA is present within the cell cytoplasmfollowing chol-DNA-HDL AuNP treatment, but does not provide informationregarding the cellular uptake of the AuNP component of the conjugate orits sub-cellular location. Following cell treatment with chol-DNA-HDLAuNPs (16 hrs), transmission electron microscopy (TEM) demonstrates thatAuNPs are present in the cell cytoplasm and free of endosomalsequestration (FIGS. 9E-9H). This is a significant finding which,without being bound by any theory, may be due to the ensemble propertiesof the HDL AuNP phospholipids complexed with cholesterylated DNA, and/orpresence of the amphiphilic APOAI protein, small conjugate size, andsurface charge. Finally, the toxicity of the chol-DNA-HDL AuNPs wasinvestigated by using a lactate dehydrogenase (LDH) release assay.Following treatment, there was no observed toxicity above backgroundlevels, even at chol-DNA-HDL AuNP concentrations well above that neededfor target RNA regulation (FIG. 10). FIG. 10 shows that HDL AuNPtreatment, DNA-HDL AuNP treatment, and DNA only treatment were notcytotoxic.

The ability of chol-DNA-HDL AuNPs to regulate target RNA was assessed ina cancer-relevant cell culture system: androgen insensitive humanprostate cancer cells (PC3) subjected to chemical hypoxia. Cellularhypoxia is a defining feature of cancer. Hypoxia inducible factor-1alpha (HIF-1α) is a transcription factor through which cancer cellsdirectly respond to hypoxia. Hypoxia was chemically induced in PC3 cellsby exposing them to cobalt chloride (CoCl₂, [300 μM]) which stabilizesHIF-1α (FIG. 11).

Stabilized HIF-1α translocates to the cell nucleus and inducestranscription from hypoxia response elements (HRE) in target genes.Directly regulated by HIF-1α binding to an upstream HRE, microRNA-210 isthe most well-known microRNA induced by hypoxia. The E2F transcriptionfactor 3 (E2F3A) has been shown to be negatively regulated by miR-210,and was chosen as the protein for analysis in this model system.

In order to confirm targeted function of the chol-DNA-HDL AuNPs,real-time quantitative PCR (RT-qPCR) was performed to measure miR-210levels in PC3 cells. U6 small nuclear RNA was used as an endogenouscontrol. Initial cell treatments were conducted in serum-free media toavoid potentially confounding chol-DNA uptake by lipoproteins present inserum. As a means of comparison, similar experiments were conducted inserum containing media (FIG. 12).

As shown in FIG. 13A, treatment with miR-210 targeted chol-DNA-HDL AuNPsresults in an 80% reduction in cellular miR-210 levels as compared toHDL-AuNP only control, and a 55% reduction as compared to freeantagomiR-210. Free cholesteryl-DNA was added on an equimolar basis tothe cholesteryl-DNA adsorbed to the surface of the chol-DNA-HDL AuNPs.HDL AuNPs (vehicle control), scrambled chol-DNA-HDL AuNPs, and the freescrambled chol-DNA did not appreciably change miR-210 levels (FIG. 13A).At 72 hours, it appears that the miR-210 levels begin to recover (FIG.14).

In order to verify delivery and function of antagomiR-210 at the proteinlevel, Western blotting was performed for E2F3A following treatment withchol-DNA-HDL AuNPs. As shown in FIG. 13B, PC3 cells express E2F3A, andthe level of which is repressed upon chemical hypoxia induction withCoCl₂, as expected. (Giannakakis, Cancer Cell Bio) Treatment of PC3cells with 10 nM chol-DNA-HDL AuNPs surface conjugated with the anti-miRto miR-210 results in a de-repression of E2F3A expression which issuperior to that of free chol-DNA anti-miR-210 added at ˜10-fold molarexcess. Vector only HDL AuNPs, scrambled chol-DNA HDL AuNP, and freecontrol scrambled sequences do not result in de-repression.

FIGS. 13A and 13B show RT-PCR and Western blot assessments ofchol-DNA-HDL AuNP-mediated knockdown of miR-210. (FIG. 13A) At themiR-210 level, chol-DNA-HDL AuNP antagomiR-210 treatment significantlyreduces miR-210 expression in the setting of CoCl₂, both in comparisonto HDL AuNP alone and in comparison to an equimolar dose of the freechol-antagomiR-210 (P<0.01, n=3). (FIG. 13B) Western blot of E2F3a, atarget of miR-210, demonstrates that chol-DNA-HDL AuNP antagomiR-210treatment de-represses E2F3A (top). GAPDH was used as protein control(bottom).

These data provide compelling evidence for hybrid chol-DNA-HDL AuNPstructures as cellular delivery vehicles for nucleic acids. Chol-DNA-HDLAuNPs enter PC3 cells, avoid endosomal sequestration, do not demonstratecellular toxicity, and, in this experiment, function to specificallytarget intracellular miR-210 and de-repress its known target, E2F3A.

The HDL AuNP platform provides significant control over the syntheticprocess, and the platform is general with regard to the identity ofnucleic acid, lipid content, final conjugate size, and surfacechemistry. Each of these factors is known to be important tonanoparticle function at the bio-nano interface. Furthermore, thebiomimetic HDL AuNP platform may provide advantages with regard tosystemic pharmacokinetics, cell targeting, and receptor-mediatedconjugate uptake through known HDL receptors, such as scavenger receptortype B-1 (SR-B1). As such, hybrid biomimetic lipoprotein agents may findsignificant utility for the targeted in vivo delivery of nucleic acidtherapeutics for any number of disease processes, includingatherosclerosis, inflammation, and cancer.

Materials and Methods

DNA and APOAI Quantification:

To measure amount of DNA on the DNA-HDL AuNP surface oligonucleotideswith fluorescent modifiers were used (Table 1). HDL-AuNPs weresynthesized using the procedure described above and their concentrationwas determined by UV-Vis. Gold nanoparticles were oxidized with KCN (40mM, final) in order to liberate fluorescently bound DNA and thefluorescence of the solution was measured. The number of DNA strands perparticle was determined by comparing the obtained fluorescencemeasurements to that of a standard curve prepared with knownconcentrations of fluor-labeled DNA.

Quantification of the number of APOAI molecules was performed similarlyusing fluorescently labeled APOAI. APOAI was labeled with Alexa-488using a commercially available protein labeling kit (Invitrogen)according to the manufacturer's instruction.

Dynamic Light Scattering/UV-Vis:

HDL-AuNPs were diluted to 10 nM concentration in water. Dynamic lightscattering (DLS) measurements were performed using a Zetasizer Nano ZS(Malvern). The hydrodynamic diameter is reported according to the numberfunction. Stability of HDL-AuNPs to aggregation in water and bufferedsaline solutions was measured using an Agilent 8453 UV-Visspectrophotometer.

Cell Culture:

Prostate adenocarcinoma cells (PC3) were obtained from American TypeCell Culture (ATCC, CRL-1435) and grown in RPMI 1640 medium supplementedwith 10% fetal bovine serum (FBS) and 1% penicillin streptomycin(Invitrogen, 11835-030). Cells were cultured in T75 flasks andsub-cultured into 6, 12, or 24 well plates. The cells were incubated at37° C. in 5% CO₂. According to experimental protocol, cells werecultured in serum free containing medium as well as under chemicallyinduced hypoxia. To chemically induce hypoxia, 300 μM cobalt chloride(CoCl₂) was added to medium at least 12 hours prior to treatment. Asdescribed herein, CoCl₂ treatment leads to a significant stabilizationof HIF-1α and RT-qPCR data demonstrates a significant increase inmiR-210 levels.

Light Microscopy:

Live cell imaging observations were made at 37° C. using a Zeiss LSM 510confocal microscope equipped with a 63×1.4 NA objective and an airstreamstage incubator (Nevtek).

Cells were grown on glass coverslips in RPMI 1640 medium supplementedwith 10% FBS and 1% penicillin streptomycin. Chemical hypoxia inductionin PC3 cells was initiated by adding 300 μM (final) cobalt chloride(CoCl₂) to the cell culture medium 12 hours prior to treatment. PC3cells were treated with DNA-HDL AuNPs (50 nM, final) and imaged atvarying time points. Prior to imaging, cell culture media was removedand the cells were washed with 1×PBS. Next, the cells were fixed in 3.7%formaldehyde (FA) in 1×PBS, and processed for immunofluorescence. Thecells were stained with antibodies directed against pan-cytokeratin usedat a 1:100 dilution (c-11, Sigma, c2931). Secondary antibodies weredonkey anti-mouse alexa-568 used at a 1:100 dilution (Invitrogen).Hoechst was used to stain the nuclei of cells and was added along withthe secondary antibody. Coverslips were placed faced down on glassslides in a mixture of 50% glycerol with 0.01 mg/mL p-phenylenediamineCoverslips were sealed with clear nailpolish (Electron MicroscopySciences). Slides were protected from light and stored at −20° C. priorto confocal imaging.

Electron Microscopy:

Cells: PC3 cells were cultured on Thermonex coverslips in RPMI 1640medium supplemented with 10% fetal bovine serum and 1% penicillinstreptomycin. Hypoxia was chemically induced by adding 300 μM (final)CoCl₂ to culture medium 12 hours prior to transfection. Cells weretreated with 50 nM (final) DNA-HDL AuNPs. Following incubation with theDNA-HDL AuNPs, the cells were washed twice with 1×PBS and then immersedin 2% paraformaldehyde/2.5% gultaraldehyde in 0.1M sodium cacodylatebuffer (SCB). The cells were then rinsed with 0.1M SCB and placed insecondary fixative containing 2% osmium tetraoxide in 0.1M SCB. Next,cells were rinsed with distilled water and stained with 3% uranylacetate. The fixed samples were rinsed with distilled water and thendehydrated in ascending grades of ethanol. Propylene oxide was used as atransitional buffer, and tissues were embedded in Epon 812 and Aralditeresin. Samples were placed in a 60° C. oven to cure. The blocks weresectioned using an ultramicrotome and then mounted on grids for TEMimaging. TEM images were obtained using a FEI Tecnai Spirit G2 operatingat 120 kV.

Particles:

TEM particle samples were prepared using 200 mesh carbon-film coatedcopper grids (Electron Microscopy Sciences). Two samples were prepared.A small aliquot of 5 nm diameter AuNPs and chol-DNA-HDL AuNPs werespotted to grids, excess was removed with filter paper, and the sampleswere allowed to dry. The samples were then stained with 3% uranylacetate (15 mins) prior to imaging. TEM images were obtained using a FEITecnai Spirit G2 operating at 120 kV.

Cytotoxicity:

Cell cytotoxicity experiments were conducted using a commerciallyavailable enzymatic colorimetric lactate dehydrogenase (LDH) assayaccording to the manufacturer's protocol (Roche Applied Sciences). LDHis an intracellular enzyme that is released into the cell culture mediafollowing cell death. The old cell growth media collected at varioustime points for the treated as well as untreated cell pools were spundown at 300 g for 10 minutes, to remove cell debris. These supernatantof the media samples were subsequently assayed for LDH levels. Toestablish the maximum LDH levels, one untreated and non-hypoxiasimulated cell pool was lysed by introduction of 1% Triton-X 100 intothe cell growth media. Fresh PC3 cell growth media was used as a blank.Samples were twenty-fold diluted with assay medium (1% Serum in DMEM).LDH activity was measured by adding the working reagent according to themanufacturer's protocol, and the samples were incubated at roomtemperature for 30 mins. LDH levels were quantifiedspectrophotometrically.

RT-qPCR for miR-210:

PC3 cells were cultured according to the protocol above. Followingtreatment, the cells were lysed and total RNA was extracted usingTRIzol® reagent (Invitrogen). Total RNA was quantified and its integrityassessed using the NanoDrop Technologies ND-100 spectrophotometer bymeasuring absorbances at 260 nm and 280 nm. Samples with A₂₆₀/A₂₈₀ ratiobetween 1.8 and 2.0 were used for analysis. Subsequently, the total RNAsamples were diluted to a concentration of 2 ng/μl. Using TaqMan™ RT Kitand TaqMan™ U6-snRNA and hsa-miR-210 RT probes, 10 ng of total RNA fromeach sample was reverse transcribed (RT) in 15 μl total reactionvolumes, as per the manufacturer's protocol. Next, RT samples were usedto setup 20 μl final volume qPCR reactions, in 384 well plates usingTaqMan™ PCR Master Mix and TaqMan™ U6-snRNA and hsa-miR-210 probes, asper the manufacturer's protocols. The qPCR reaction was carried outusing an ABI Prism Model 7900HT. Data was analyzed using the comparativeC_(t) method using U6 small nuclear RNA as an endogenous control.

Western Blot:

PC3 cells were cultured as above until approximately 80% confluent. Thecells were treated with targeted and scrambled control chol-DNA (100 and500 nM), HDL AuNP vector (10 and 50 nM), and targeted and scrambledcontrol chol-DNA-HDL AuNPs (10 and 50 nM). PC3 cells were exposed for 24hours. Next, the cells were washed×2 with 1×PBS. Total cellular proteinwas extracted using mammalian protein extraction reagent (M-PER, Thermo)according to the manufacturer's protocol. The protein concentration fromeach sample was measured using Coomassie protein staining according tothe Bradford assay using a bovine serum albumin (BSA) standard curve andcolorimetric readout at 570 nm (BioRad). The total proteinconcentrations from each sample were made equivalent (20 μg), mixed withloading buffer, and then subjected to electrophoretic separation. A4-20% Tris-HCL Criterion polyacrylamide gel was used for separation(200V, ˜1 hour). The gel was transferred to a nitrocellulose membraneovernight at 4° C. Following transfer, the membrane was washed in water(5 min) and then allowed to dry for ˜1 hour. The membrane was re-wettedin methanol and then transferred to Ponceau stain×5 mins. Following abrief rinse, the membrane was imaged (Epson scanner). Prior toimmunoblotting, the membrane was washed in TBST (Tween=0.1%)×20 mins.Blocking of the membrane was then completed using 5% milk/TB ST for 1hour. The primary E2F3A antibody (polyclonal, rabbit, C-18 Santa Cruz³,1:200) was added and allowed to incubate overnight at 4° C. The membraneis then washed for 10 minutes in TBST×3. The secondary antibody (goatanti-rabbit IgG, HRP-conjugate, 1:10,000, Jackson ImmunoResearch) isthen added in 5% milk/TBST and allowed to incubate×1 hour at roomtemperature (RT). Finally, the membrane was developed with ECL Plus (GEHealthcare) colorimetric reagent for 5 mins at RT. The membrane was thenimaged. GAPDH was used as a control. GAPDH immunoblotting was performedsimilarly to E2F3A. The GAPDH antibody (mouse, 1:20,000) isHRP-conjugated (Sigma), and was allowed to incubate for 1 hour at RT.

Example 5

This prophetic example shows methods that can be used to release nucleicacids from structures described herein. In particular, nucleic acid-HDLAuNPs with a modular nucleic acid component may be used for controllingthe release of nucleic acid from the AuNP surface by various stimulisuch as, for example, ex vivo (e.g. light), physiologic (e.g. reducingintracellular environment), or pathologic (e.g. reactive oxygen speciesor low pH) triggers.

DNA-HDL AuNP structures may be fabricated using Au—S coupling of DNAoligonucleotides to the surface of a Au nanostructure core such that thestructure effectively sequesters the gene regulating portion of the DNAsequence on the surface of the structure, and fail to make it availableto the intracellular cytoplasmic machinery required to regulate geneexpression. Engineering nucleic acid triggered release mechanisms intothe DNA-HDL AuNP platform provides a way to test the mechanism of actionof the DNA-HDL AuNP structures once inside cells, compare materials withdifferent release chemistries, and introduce flexibility into theplatform to address bio-nano interfacial challenges (e.g. endosomalsequestration) that may surface after initial testing.

In one set of embodiments, DNA-HDL AuNP structures fabricated under thisobjective will proceed according to FIG. 2B and FIG. 15. As shown inFIG. 15, functionalized oligonucleotides, represented by component 59,can be fabricated to include, for example, four distinct units 60, 62,64 and 66. In one set of embodiments, block 60 is an end-modificationthat can allow component 59 to attach to a portion of a structure (e.g.,a shell or a nanostructure core). Block 62 is a linker that may attachblock 60 to a release linker, represented by block 64. The releaselinker may allow the coupling and release of a regulatory nucleic acid66 from component 59. Examples of specific chemical compounds that canbe used for each of units 60, 62, 64 and 66 are shown in FIG. 15.PEG=polyethyleneglycol andSPDP=N-succinimidyl-3-(2-pyridyldithio)propionate.

Solid-phase phosphoramidite chemistry is an example of a method that canbe used to fabricate functionalized oligonucleotides. Directedmanipulation of each block will be conducted in order to determine howeach changes nucleic acid release and, ultimately, in vitro function.First, 3′-thiol end modifications (block 60) can be manipulated in orderto drive the attachment and loading of DNA to the AuNP surface.Manipulation of the 3′-thiol moiety, for example, may be used tooptimize the loading of all DNA-HDL AuNP surface components. Next, andshowing the example of intracellular reduction and disulfide ligandexchange as the method of nucleic acid release, a release linker, block64, will be systematically varied, including removed, in order to test,specifically, how the chemical identity of the linker impacts nucleicacid release. In the case of a disulfide, glutathione mediated ligandexchange and nucleic acid release will be studied in solution in orderto systematically assess how the tether impacts release form the surfaceof DNA-HDL AuNPs. Next, different tethers (block 62), including none,will be added between the thiol (block 60) and linking (block 64)elements in order to assess how tether length changes nucleic acidrelease. There are a number of thiol, tether, and linking chemistriesdirectly compatible with phosphoramidite chemistry and solid phasesynthesis, and others that can be manually added using straight-forwardconjugation chemistries (e.g. EDC/NHS). FIG. 15 demonstrates some commonphosphoramidites and combinatorial cross-linking strategies.

Finally, the regulatory nucleic acid represents the unit 66. For theseexperiments, single-stranded DNA will be focused on due to the broadpotential applications of DNA introduced into cells and due to itsstability. The DNA antago-miR-210 and scrambled sequences will bestudied, although other oligonucleotides such as those described hereincan be used. In each case, straight-forward assessment of nucleic acidrelease will take place in solution using appropriate chemical gradients(e.g. pH or glutathione titration) or light. DNA stability may beenhanced by binding to the surface of the AuNP. While nucleic acidstability on AuNPs is related to density, the HDL AuNP platform mayprovide advantages by sequestering the nucleic acid within thephospholipid layer, and preventing access by nucleases. This may welldepend upon other properties of the attached oligo including tetherlength. By using standard fluorescence assays and melting transitionassays, both the stability and recognition properties of the immobilizedDNA oligonucleotide will be measured.

Example 6

This example describes a structure with a shell having a mixed monolayerconfiguration to allow for covalent bonding of therapeuticoligonucleotides to the core of the structure.

A mixed monolayer structure may allow for covalent bonding oftherapeutic oligonucleotides to the nanostructure core via a linkingelement, in this case the carboxylic acid group of mercaptohexadecanoicacid (MHA). By integrating MHA with phospholipids, t nucleic acidsequences can be conjugated to nanoparticles and, in some cases, mayovercome endosomal sequestration.1-Ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride andN-hydroxysulfosuccinimide (EDC/NHS) chemistry is a well-establishedmethod of activating carboxylic groups to increase their reactivitytoward primary amines, thus generating a stable amide bond. Here,EDC/NHS was used to facilitate amide bond formation between thecarboxylic acid group of MHA and an oligonucleotide end-modified with aprimary amine.

The use of short nucleic acid sequences to selectively bind to mRNAsequences within cells is a well established method of gene regulation.In this example, a DNA sequence shown to regulate the expression ofsurvivin, an anti-apoptotic protein near universally upregulated inhuman cancer, was chosen as the model nucleic acid therapeutic. Mixedmonolayer AuNPs covalently coupled to anti-survivin oligonucleotideshave the potential to selectively bind intracellular survivin mRNA,knockdown survivin protein expression, and induce cancer cell death.

Materials and Methods

Synthesis of a Mixed-Monolayer Nanoparticle of Phospholipids and MHA:

The schematic for the synthesis of the mixed-monolayer AuNP is shown inFIG. 4. Thiol modified phospholipids,1,2-bis(11-mercaptoundecanoyl)-sn-glycero-3-phosphocholine (C10) and1,2-bis(16-mercaptohexadecanoyl)-sn-glycero-3-phosphocholine (C15), andmercaptohexadecanoic acid (MHA) were adsorbed onto the surface of 10 nmAuNPs. In a typical synthesis, 10 nm AuNPs were suspended in a 1:1mixture of ethanol and water and mixed with a 100-fold excess ofappropriate lipids. Solutions of lipids and AuNPs were mixed overnight.Unreacted lipids were removed from solutions of conjugated lipid-AuNPsusing dialysis [10 kD molecular weight cut off (MWCO), SnakeSkindialysis tubing (Thermo Scientific)]. Various ratios of lipid (C10 orC15) to MHA were employed in order to optimize coupling ofoligonucleotides to the nanostructure core surface.

Nanostructure Characterization:

Dynamic light scattering (DLS, Malvern) measurements were used toconfirm chemical functionalization of the AuNPs by demonstrating anincrease in hydrodynamic diameter. Transmission electron microscopy(TEM, FEI Spirit) was used to image the lipid layer on the surface ofthe AuNPs. The lipid layer was identified using uranyl acetate staining.Finally, the use of sodium bicarbonate was used to qualitatively verifythe presence of the carboxylic end-groups of AuNP surface adsorbed MHAmolecules.

Immobilization of DNA:

The antisense survivin oligonucleotide sequence was chosen for thisexperiment (5′-CCCAGCCTTCCAGCTCCTTG-3′). The sequence was synthesizedusing standard solid phase phosphoramidite chemistry, and capped with a5′ amine group for EDC/NHS coupling to the carboxylic acid moiety ofMHA. A 3′ fluorophore label (fluoroescein) was used in order to easilyquantify conjugate AuNP loading of oligonucleotides and to serve asvisual labels for cell culture experiments. Modified antisenseoligonucleotides were purified using high performance liquidchromatography. Coupling of antisense survivin DNA to the surface ofmixed-monolayer AuNPs was determined using a fluorescent plate reader tomeasure the concentration of fluorescently labeled DNA on the AuNPs.Using a standard dilution series of the labeled oligonucleotide, theapproximate number of DNA strands per particle was determined.

Nanoparticle Uptake in Cancer Cells:

Mixed-monolayer structures were added to human prostate cancer cells(LnCaP) grown in culture, and imaged using confocal fluorescencemicroscopy. LnCaP cells were grown in monolayer cell culture to 60-80%confluence in glass bottom live-cell imaging dishes. Mixed-monolayerDNA-functionalized AuNPs were transfected at a concentration of 100 pM(12 hours) and compared to a control group of cells incubated withphosphate buffered saline (PBS). After incubation, the cell monolayerswere washed with PBS (three times), and Leibovitz's media was added forconfocal microscopy imaging of live cells.

Results

Nanoparticle Characterization:

Dynamic light scattering was used to measure the size of thenanoparticles before and after surface modification (Table 3).Unmodified AuNPs have a hydrodynamic radius of 9±1 nm. Upon addition ofphospholipids and MHA, the diameter of the nanoparticle increasessignificantly, and supports the presence of the mixed lipid monolayer onthe surface of the particles. Overall, the hydrodynamic diameter of theC15 lipid is greater than the C10 lipid, which agrees with the alkyltail length differences of C15 versus C10 lipids.

TABLE 3 Nanoparticle Lipid:MHA Hydrodynamic Conjugate Ratio Diameter(nm) 10 nm AuNPs  9 ± 1 C10 Conjugate 10:1 12 ± 1 20:1 12 ± 1 50:1 12 ±1 C15 Conjugate 10:1 13 ± 1 20:1 14 ± 1 50:1 13 ± 1

FIGS. 16A and 16B are TEM images of the C10 and C15 lipid mixedmonolayer structures, each with a 10:1 ratio of phospholipid to MHA.Following negative staining with uranyl acetate, a halo-like ring isevident around each structure supporting the presence of themixed-monolayer on the surface of the nanostructure core.

The presence of the carboxylic group was confirmed qualitatively via theaddition of sodium bicarbonate and the evolution of gas (carbon dioxide)bubbles. The reaction for this experiment is: R—COOH+NaHCO₃R→COO⁻Na⁺+H₂O(l)+CO₂ (g).

Immobilization of DNA:

Fluorescence measurements demonstrate the capability of mixed-monolayerphospholipid-functionalized AuNPs to bind DNA. A standard curve of freefluorescently labeled oligonucleotides was employed to determine theconcentration and number of DNA sequences bound to the mixed-monolayernanoparticles (Table 4). In general, the results show an increase in thenumber of oligonucleotides bound to the AuNP surface as the ratio ofphospholipids to MHA increases. Optimal binding of oligonucleotides tothe mixed monolayer AuNPs was observed for the C10 versus C15phospholipid.

TABLE 4 Nanoparticle Lipid:MHA DNA per Conjugate Ratio FluorescenceNanoparticle C10 Conjugate 10:1 2295 1 20:1 11822 13 50:1 15040 7 C15Conjugate 10:1 8961 5 20:1 9243 9 50:1 6357 3

Nanoparticle Uptake in Cancer Cells:

LnCaP prostate cancer cells were transfected with the mixed-monolayerDNA-functionalized AuNPs and imaged using confocal microscopy (FIG. 17).Cells were transfected with AuNPs functionalized with the mixedmonolayer of C10 lipids and MHA or C15 lipids and MHA in a 10:1 ratio.In each case, the mixed-monolayer AuNPs were surface functionalized withfluorescein-labeled DNA. The images in FIG. 17 demonstrate the lack offluorescence in the control group of cells—the anticipated result.Co-localization of nanoparticle fluorescent signal and LnCaP cells inphase implies that both conjugates effectively interact with LnCaPcells. The sub-cellular localization of the mixed-monolayernanoparticles cannot be verified from these images.

Results demonstrate that AuNPs can be fabricated with a mixed monolayerof thiol-modified phospholipids and MHA. By using MHA as a surfacecomponent of the AuNPs, covalent coupling of amine-terminated DNAoligonucleotides can be achieved using well-established EDC/NHS couplingchemistry. The mixed-monolayer nanoparticles containing C10 lipidsprovided a suitable chemical background for the covalent attachment ofamine-terminated oligonucleotides to co-adsorbed MHA molecules.Presumably, in some embodiments, the longer alkyl tail length of the C15versus C10 lipid may cause increased steric hindrance to productive MHAcoupling to incoming amine-terminated DNA sequences.

In order to determine the feasibility of using DNA-functionalizedmixed-monolayer AuNPs as therapeutic agents, their ability to be takenup into prostate cancer cells grown in culture was assessed. Initialcell uptake experiments imply that the nanoparticle conjugates interactfavorably with cancer cells. Future studies will focus on theinteraction of the mixed monolayer AuNP DNA conjugates with cancer cellsand more thoroughly assess their sub-cellular distribution andbiological function.

The results of this experiment demonstrate a successful approach ofsurface functionalizing AuNPs with both lipids and DNA in order topotentially realize the benefits of both of these biological moleculesin the context of cellular transfection and gene regulation.

These results also open up the possibility for future work involvingother applications with proteins or other biologically importantmolecules coupled to the surface of the mixed-monolayer AuNPs usingfacile EDC/NHS coupling chemistry.

While several embodiments of the present invention have been describedand illustrated herein, those of ordinary skill in the art will readilyenvision a variety of other means and/or structures for performing thefunctions and/or obtaining the results and/or one or more of theadvantages described herein, and each of such variations and/ormodifications is deemed to be within the scope of the present invention.More generally, those skilled in the art will readily appreciate thatall parameters, dimensions, materials, and configurations describedherein are meant to be exemplary and that the actual parameters,dimensions, materials, and/or configurations will depend upon thespecific application or applications for which the teachings of thepresent invention is/are used. Those skilled in the art will recognize,or be able to ascertain using no more than routine experimentation, manyequivalents to the specific embodiments of the invention describedherein. It is, therefore, to be understood that the foregoingembodiments are presented by way of example only and that, within thescope of the appended claims and equivalents thereto, the invention maybe practiced otherwise than as specifically described and claimed. Thepresent invention is directed to each individual feature, system,article, material, kit, and/or method described herein. In addition, anycombination of two or more such features, systems, articles, materials,kits, and/or methods, if such features, systems, articles, materials,kits, and/or methods are not mutually inconsistent, is included withinthe scope of the present invention.

All definitions, as defined and used herein, should be understood tocontrol over dictionary definitions, definitions in documentsincorporated by reference, and/or ordinary meanings of the definedterms.

The indefinite articles “a” and “an,” as used herein in thespecification and in the claims, unless clearly indicated to thecontrary, should be understood to mean “at least one.”

The phrase “and/or,” as used herein in the specification and in theclaims, should be understood to mean “either or both” of the elements soconjoined, i.e., elements that are conjunctively present in some casesand disjunctively present in other cases. Multiple elements listed with“and/or” should be construed in the same fashion, i.e., “one or more” ofthe elements so conjoined. Other elements may optionally be presentother than the elements specifically identified by the “and/or” clause,whether related or unrelated to those elements specifically identified.Thus, as a non-limiting example, a reference to “A and/or B”, when usedin conjunction with open-ended language such as “comprising” can refer,in one embodiment, to A only (optionally including elements other thanB); in another embodiment, to B only (optionally including elementsother than A); in yet another embodiment, to both A and B (optionallyincluding other elements); etc.

As used herein in the specification and in the claims, “or” should beunderstood to have the same meaning as “and/or” as defined above. Forexample, when separating items in a list, “or” or “and/or” shall beinterpreted as being inclusive, i.e., the inclusion of at least one, butalso including more than one, of a number or list of elements, and,optionally, additional unlisted items. Only terms clearly indicated tothe contrary, such as “only one of” or “exactly one of,” or, when usedin the claims, “consisting of,” will refer to the inclusion of exactlyone element of a number or list of elements. In general, the term “or”as used herein shall only be interpreted as indicating exclusivealternatives (i.e. “one or the other but not both”) when preceded byterms of exclusivity, such as “either,” “one of,” “only one of,” or“exactly one of.” “Consisting essentially of,” when used in the claims,shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase “atleast one,” in reference to a list of one or more elements, should beunderstood to mean at least one element selected from any one or more ofthe elements in the list of elements, but not necessarily including atleast one of each and every element specifically listed within the listof elements and not excluding any combinations of elements in the listof elements. This definition also allows that elements may optionally bepresent other than the elements specifically identified within the listof elements to which the phrase “at least one” refers, whether relatedor unrelated to those elements specifically identified. Thus, as anon-limiting example, “at least one of A and B” (or, equivalently, “atleast one of A or B,” or, equivalently “at least one of A and/or B”) canrefer, in one embodiment, to at least one, optionally including morethan one, A, with no B present (and optionally including elements otherthan B); in another embodiment, to at least one, optionally includingmore than one, B, with no A present (and optionally including elementsother than A); in yet another embodiment, to at least one, optionallyincluding more than one, A, and at least one, optionally including morethan one, B (and optionally including other elements); etc.

It should also be understood that, unless clearly indicated to thecontrary, in any methods claimed herein that include more than one stepor act, the order of the steps or acts of the method is not necessarilylimited to the order in which the steps or acts of the method arerecited.

In the claims, as well as in the specification above, all transitionalphrases such as “comprising,” “including,” “carrying,” “having,”“containing,” “involving,” “holding,” “composed of,” and the like are tobe understood to be open-ended, i.e., to mean including but not limitedto. Only the transitional phrases “consisting of” and “consistingessentially of” shall be closed or semi-closed transitional phrases,respectively, as set forth in the United States Patent Office Manual ofPatent Examining Procedures, Section 2111.03.

1. A structure comprising: a nanostructure core; a shell comprising alipid surrounding and attached to the nanostructure core; and anoligonucleotide adapted to regulate gene expression associated with atleast a portion of the shell, wherein the structure is adapted tosequester cholesterol.
 2. (canceled)
 3. A structure comprising: ananostructure core; and a cholesterol-modified oligonucleotideassociated with the nanostructure core.
 4. A nanostructure comprising anoligonucleotide adapted to regulate gene expression, a lipid, and anapolipoprotein.
 5. (canceled)
 6. A method comprising: delivering thestructure of claim 1 to a subject or a biological sample; and regulatinggene expression in the subject or biological sample.
 7. A pharmaceuticalcomposition, comprising: the structure of claim 1; and one or morepharmaceutically acceptable carriers, additives, and/or diluents.
 8. Akit for diagnosing, preventing, treating or managing a disease or bodilycondition comprising: a composition comprising a plurality of structuresof claim 1; and instructions for use of the composition for diagnosing,preventing, treating or managing a disease or bodily condition. 9.-14.(canceled)
 15. A structure as in claim 1, wherein the shell comprises alipid bilayer.
 16. A structure as in claim 15, wherein the lipid bilayercomprises a phospholipid. 17-27. (canceled)
 28. A structure as in claim1, wherein the shell comprises an apolipoprotein.
 29. (canceled)
 30. Astructure as in claim 28, wherein the apolipoprotein is apolipoproteinA-I, apolipoprotein A-II, or apolipoprotein E. 31-46. (canceled)
 47. Astructure as in claim 1, wherein the nanostructure core has a largestcross-sectional dimension of less than or equal to about 30 nm. 48.-51.(canceled)
 52. A structure as in claim 1, wherein the nanostructure corecomprises an inorganic material. 53-55. (canceled)
 56. A structure as inclaim 1, wherein the nanostructure core comprises a polymer, or issubstantially formed from a polymer. 57-83. (canceled)
 84. A structureas in claim 1, wherein the oligonucleotide has a length of about 10 toabout 100 nucleotides or base pairs in length. 85-86. (canceled)
 87. Astructure as in claim 1, wherein the oligonucleotide comprises antisenseDNA, siRNA, or microRNA.
 88. A method as in claim 6, further comprisingreleasing at least a portion of the oligonucleotide from the structure.89. A structure as in claim 1, wherein the oligonucleotide is covalentlyor near-covalently bonded to the nanostructure core or to the shell. 90.A structure as in claim 1, wherein the oligonucleotide is physisorbedonto a portion of the shell.
 91. (canceled)
 92. A structure as in claim1, wherein the oligonucleotide is modified with a lipid.
 93. A structureas in claim 1, wherein the oligonucleotide is cholesterylated.
 94. Astructure as in claim 1, wherein the oligonucleotide comprises5′-cholesteryl DNA or 3′-cholesteryl DNA. 95-96. (canceled)
 97. Astructure as in claim 1, wherein the structure is both a therapeutic anda diagnostic agent.
 98. A structure as in claim 1, wherein the structureis adapted to deliver therapeutic oligonucleotides and/or is adapted tobe used as an intracellular diagnostic sensor.
 99. A structure as inclaim 1, wherein the oligonucleotide comprises a fluorophore that isadapted to change in fluorescence intensity upon binding to a targetprotein or a small molecule.